Star CCM+ User Guide

CCM USER GUIDESTAR-CD VERSION 4.02 CONFIDENTIAL — FOR AUTHORISED USERS ONLY © 2006 CD-adapco TABLE OF CONTENTS OVERVIEW 1 COMPUTATIONAL ANALYSIS PRINCIPLES Introduction ............................................................................................................... 1-1 The Basic Modelling Process .................................................................................... 1-1 Spatial description and volume discretisation ........................................................... 1-2 Solution domain definition .............................................................................. 1-3 Mesh definition ................................................................................................ 1-4 Mesh distortion ................................................................................................ 1-5 Mesh distribution and density ......................................................................... 1-6 Mesh distribution near walls ........................................................................... 1-7 Moving mesh features ..................................................................................... 1-8 Problem characterisation and material property definition ....................................... 1-8 Nature of the flow ............................................................................................ 1-9 Physical properties ........................................................................................... 1-9 Force fields and energy sources ...................................................................... 1-9 Initial conditions ............................................................................................ 1-10 Boundary description .............................................................................................. 1-10 Boundary location ......................................................................................... 1-11 Boundary conditions ...................................................................................... 1-11 Numerical solution control ..................................................................................... 1-13 Selection of solution procedure ..................................................................... 1-13 Transient flow calculations with PISO .......................................................... 1-13 Steady-state flow calculations with PISO ..................................................... 1-15 Steady-state flow calculations with SIMPLE ................................................ 1-16 Transient flow calculations with SIMPLE .................................................... 1-17 Effect of round-off errors .............................................................................. 1-18 Choice of the linear equation solver .............................................................. 1-19 Monitoring the calculations .................................................................................... 1-19 Model evaluation .................................................................................................... 1-20 BASIC STAR-CD FEATURES Introduction ............................................................................................................... 2-1 Running a STAR-CD Analysis ................................................................................. 2-2 Using the script-based procedure .................................................................... 2-3 Using STAR-Launch ....................................................................................... 2-8 pro-STAR Initialisation .......................................................................................... 2-12 Input/output window ..................................................................................... 2-13 Main window ................................................................................................. 2-15 i 2 Version 4.02 3 The menu bar .................................................................................................2-16 General Housekeeping and Session Control ...........................................................2-18 Basic set-up ....................................................................................................2-18 Screen display control ....................................................................................2-18 Error messages ...............................................................................................2-19 Error recovery ................................................................................................2-20 Session termination ........................................................................................2-21 Set Manipulation .....................................................................................................2-21 Table Manipulation .................................................................................................2-24 Basic functionality .........................................................................................2-24 The table editor ..............................................................................................2-26 Useful points ..................................................................................................2-31 Plotting Functions ....................................................................................................2-31 Basic set-up ....................................................................................................2-31 Advanced screen control ................................................................................2-32 Screen capture ................................................................................................2-33 The Users Tool ........................................................................................................2-35 Getting On-line Help ...............................................................................................2-35 The STAR GUIde Environment ..............................................................................2-38 Panel navigation system .................................................................................2-40 STAR GUIde usage .......................................................................................2-41 General Guidelines ..................................................................................................2-41 MATERIAL PROPERTY AND PROBLEM CHARACTERISATION Introduction ...............................................................................................................3-1 The Cell Table ...........................................................................................................3-1 Cell indexing ....................................................................................................3-3 Multi-Domain Property Setting .................................................................................3-5 Setting up models .............................................................................................3-6 Compressible Flow ....................................................................................................3-9 Setting up compressible flow models ..............................................................3-9 Useful points on compressible flow ...............................................................3-10 Non-Newtonian Flow ..............................................................................................3-11 Setting up non-Newtonian models .................................................................3-11 Useful points on non-Newtonian flow ...........................................................3-11 Turbulence Modelling .............................................................................................3-12 Wall functions ................................................................................................3-13 Two-layer models ..........................................................................................3-13 Low Re models ..............................................................................................3-14 Hybrid wall boundary condition ....................................................................3-14 ii Version 4.02 4 Reynolds Stress models ................................................................................. 3-15 DES models ................................................................................................... 3-15 LES models ................................................................................................... 3-15 Changing the turbulence model in use .......................................................... 3-16 Heat Transfer In Solid-Fluid Systems ..................................................................... 3-16 Setting up solid-fluid heat transfer models .................................................... 3-17 Heat transfer in baffles .................................................................................. 3-18 Useful points on solid-fluid heat transfer ...................................................... 3-19 Buoyancy-driven Flows and Natural Convection ................................................... 3-20 Setting up buoyancy-driven models .............................................................. 3-20 Useful points on buoyancy-driven flow ........................................................ 3-20 Fluid Injection ......................................................................................................... 3-21 Setting up fluid injection models ................................................................... 3-22 BOUNDARY AND INITIAL CONDITIONS Introduction ............................................................................................................... 4-1 Boundary Location .................................................................................................... 4-1 Command-driven facilities .............................................................................. 4-2 Boundary set selection facilities ...................................................................... 4-3 Boundary listing .............................................................................................. 4-3 Boundary Region Definition ..................................................................................... 4-5 Inlet Boundaries ........................................................................................................ 4-9 Introduction ..................................................................................................... 4-9 Useful points .................................................................................................. 4-10 Outlet Boundaries ................................................................................................... 4-11 Introduction ................................................................................................... 4-11 Useful points .................................................................................................. 4-12 Pressure Boundaries ................................................................................................ 4-12 Introduction ................................................................................................... 4-12 Useful points .................................................................................................. 4-13 Stagnation Boundaries ............................................................................................ 4-14 Introduction ................................................................................................... 4-14 Useful points .................................................................................................. 4-15 Non-reflective Pressure and Stagnation Boundaries ............................................... 4-16 Introduction ................................................................................................... 4-16 Useful points .................................................................................................. 4-18 Wall Boundaries ...................................................................................................... 4-19 Introduction ................................................................................................... 4-19 Thermal radiation properties ......................................................................... 4-20 Solar radiation properties .............................................................................. 4-20 iii Version 4.02 5 Other radiation modelling considerations ......................................................4-21 Useful points ..................................................................................................4-22 Baffle Boundaries ....................................................................................................4-23 Introduction ....................................................................................................4-23 Setting up models ...........................................................................................4-24 Thermal radiation properties ..........................................................................4-25 Solar radiation properties ...............................................................................4-26 Other radiation modelling considerations ......................................................4-26 Useful points ..................................................................................................4-27 Symmetry Plane Boundaries ...................................................................................4-27 Cyclic Boundaries ...................................................................................................4-27 Introduction ....................................................................................................4-27 Setting up models ...........................................................................................4-28 Useful points ..................................................................................................4-30 Cyclic set manipulation ..................................................................................4-31 Free-stream Transmissive Boundaries ....................................................................4-32 Introduction ....................................................................................................4-32 Useful points ..................................................................................................4-33 Transient-wave Transmissive Boundaries ...............................................................4-34 Introduction ....................................................................................................4-34 Useful points ..................................................................................................4-35 Riemann Boundaries ...............................................................................................4-36 Introduction ....................................................................................................4-36 Useful points ..................................................................................................4-37 Attachment Boundaries ...........................................................................................4-38 Useful points ..................................................................................................4-39 Radiation Boundaries ..............................................................................................4-39 Useful points ..................................................................................................4-40 Phase-Escape (Degassing) Boundaries ...................................................................4-40 Monitoring Regions .................................................................................................4-40 Boundary Visualisation ...........................................................................................4-41 Solution Domain Initialisation ................................................................................4-42 Steady-state problems ....................................................................................4-42 Transient problems .........................................................................................4-42 CONTROL FUNCTIONS Introduction ...............................................................................................................5-1 Analysis Controls for Steady-State Problems ...........................................................5-1 Analysis Controls for Transient Problems ................................................................5-4 Default (single-transient) solution mode .........................................................5-4 Version 4.02 iv 6 7 8 Load-step based solution mode ....................................................................... 5-6 Load step characteristics .................................................................................. 5-6 Load step definition ......................................................................................... 5-8 Solution procedure outline .............................................................................. 5-9 Other transient functions ............................................................................... 5-14 Solution Control with Mesh Changes ..................................................................... 5-15 Mesh-changing procedure ............................................................................. 5-15 Solution-Adapted Mesh Changes ........................................................................... 5-17 POROUS MEDIA FLOW Setting Up Porous Media Models ............................................................................. 6-1 Useful Points ............................................................................................................. 6-4 THERMAL AND SOLAR RADIATION Radiation Modelling for Surface Exchanges ............................................................ 7-1 Radiation Modelling for Participating Media ........................................................... 7-3 Capabilities and Limitations of the DTRM Method ................................................. 7-5 Capabilities and Limitations of the DORM Method ................................................. 7-7 Radiation Sub-domains ............................................................................................. 7-8 CHEMICAL REACTION AND COMBUSTION Introduction ............................................................................................................... 8-1 Local Source Models ................................................................................................ 8-2 Presumed Probability Density Function (PPDF) Models ......................................... 8-3 Single-fuel PPDF ............................................................................................. 8-3 Multiple-fuel PPDF ......................................................................................... 8-9 Regress Variable Models ........................................................................................ 8-10 Complex Chemistry Models ................................................................................... 8-11 Setting Up Chemical Reaction Schemes ................................................................. 8-14 Useful general points for local source and regress variable schemes ........... 8-16 Chemical Reaction Conventions ................................................................... 8-18 Useful points for PPDF schemes ................................................................... 8-18 Useful points for complex chemistry models ................................................ 8-21 Useful points for ignition models .................................................................. 8-21 Setting Up Advanced I.C. Engine Models .............................................................. 8-22 Coherent Flame model (CFM) ...................................................................... 8-24 Extended Coherent Flame model (ECFM) .................................................... 8-26 Extended Coherent Flame model 3Z (ECFM-3Z) — spark ignition ............ 8-28 Extended Coherent Flame model 3Z (ECFM-3Z) — compression ignition . 8-29 Useful points for ECFM models .................................................................... 8-30 Level Set model ............................................................................................. 8-31 Write Data sub-panel ..................................................................................... 8-32 v Version 4.02 9 The Arc and Kernel Tracking ignition model (AKTIM) ...............................8-33 Useful points for the AKTIM model .............................................................8-35 The Double-Delay autoignition model ..........................................................8-37 NOx Modelling ........................................................................................................8-39 Soot Modelling ........................................................................................................8-39 Coal Combustion Modelling ...................................................................................8-41 Stage 1 ............................................................................................................8-41 Stage 2 ............................................................................................................8-42 Useful notes ...................................................................................................8-44 Switches and constants for coal modelling ....................................................8-45 Special settings for the Mixed-is-Burnt and Eddy Break-Up models ............8-46 LAGRANGIAN MULTI-PHASE FLOW Setting Up Lagrangian Multi-Phase Models .............................................................9-1 Data Post-Processing .................................................................................................9-4 Static displays ..................................................................................................9-5 Trajectory displays ...........................................................................................9-8 Engine Combustion Data Files ..................................................................................9-9 Useful Points ...........................................................................................................9-10 10 EULERIAN MULTI-PHASE FLOW Introduction .............................................................................................................10-1 Setting up multi-phase models ................................................................................10-1 Useful points on Eulerian multi-phase flow ..................................................10-4 11 FREE SURFACE AND CAVITATION Free Surface Flows ..................................................................................................11-1 Setting up free surface cases ..........................................................................11-1 Cavitating Flows ......................................................................................................11-5 Setting up cavitation cases .............................................................................11-5 12 ROTATING AND MOVING MESHES Rotating Reference Frames .....................................................................................12-1 Models for a single rotating reference frame .................................................12-1 Useful points on single rotating frame problems ...........................................12-1 Models for multiple rotating reference frames (implicit treatment) ..............12-2 Useful points on multiple implicit rotating frame problems ..........................12-4 Models for multiple rotating reference frames (explicit treatment) ...............12-5 Useful points on multiple explicit rotating frame problems ..........................12-8 Moving Meshes .......................................................................................................12-9 Basic concepts ................................................................................................12-9 Setting up models .........................................................................................12-10 Useful points ................................................................................................12-13 vi Version 4.02 ...................... 13-1 Useful points on multi-component mixing ...... 12-18 Regular sliding interfaces ............................................................................................................................................................................................................................................................................. 12-27 Mesh Region Exclusion ............ 13-5 Film stripping .................. 13-5 Setting up liquid film models ................................................... 12-28 Action commands .................................................. 12-15 Useful points ........................................................... 12-28 Introduction ................................................................................................................................................. 14-5 Material property subroutines ........................................................... 14-4 Description of UFILE Routines .............................................. 12-28 Basic concepts ............................................... 13-3 Aeroacoustic Analysis ...................................................... 12-28 Moving Mesh Pre. 12-13 Cell-layer Removal/Addition ............................................................................................. 14-1 Useful points ....................................................... 12-29 Status setting commands ............................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................. 13-3 Setting up aeroacoustic models .................................................................... 13-7 14 USER PROGRAMMING Introduction .............................................................Automatic Event Generation for Moving Piston Problems ............................................ 12-18 Cell Attachment and Change of Fluid Type ................. 14-9 Source subroutines .......................................................................... 13-3 Useful points on aeroacoustic analyses ................................................................................. 12-22 Setting up models ............................................................................................. 14-11 Free surface / cavitation subroutines .............................................................................................................. 12-22 Basic concepts ........................................... 12-14 Setting up models ............................................................... 13-4 Liquid Films ............. 14-11 Lagrangian multi-phase subroutines ...........................02 vii ..................... 12-23 Useful points ....... 12-30 13 OTHER PROBLEM TYPES Multi-component Mixing ............................................................................ 14-1 Subroutine Usage ........................ 14-10 Radiation modelling subroutines .............................................. 13-1 Setting up multi-component models .................... 14-12 Version 4....................................................... 14-5 Boundary condition subroutines ...................................................................................................................................and Post-processing .......................................................... 14-6 Turbulence modelling subroutines .................................................................................. 12-18 Sliding Meshes ............................................................................. 12-14 Basic concepts ............................................................................................................................ .....................17-14 The StarWatch Utility ..............................17-1 File Handling .............................................................................16-2 Panel creation .......17-7 File manipulation ...................17-1 File relationships ..................................................................15-3 Example Output .................15-1 Permanent Output .......................................................................................................................................................................................................................15-1 Input-data summary ................14-14 Chemical reaction subroutines ....................................17-12 Resizing pro-STAR ...........................................................................................................................14-18 Sample Listing .......................14-17 Solution control subroutines ........................................................................................................................................................15-1 Run-time output ..........................................................................................................................Liquid film subroutines ................15-4 16 pro-STAR CUSTOMISATION Set-up Files ....................................................................................................................................................................................................................................................................................................................................................14-22 15 PROGRAM OUTPUT Introduction ............................................................14-15 Rotating reference frame subroutines ......................................................................14-20 User Coding in parallel runs ...........................................................17-14 Use of temporary files by pro-STAR ...16-9 17 OTHER STAR-CD FEATURES AND CONTROLS Introduction ......................................................16-1 Panels .........................................................................17-12 pro-STAR environment variables ......................................................15-3 Optional Output ..............................................17-13 Special pro-STAR executables ..14-16 Miscellaneous flow characterisation subroutines .................................................................................................................................................................17-1 Naming conventions .................................................15-3 Printout of Field Values ................................................................................................................................................................................................................................17-1 Commonly used files .................................................................................16-6 Function Keys ........................................................................................................................................................................................................................................................................................17-15 viii Version 4..................................14-16 Moving mesh subroutines ......................02 .................14-14 Eulerian multi-phase subroutines ........................................16-6 Macros .....................................................................................16-5 Panel manipulation ...................................................................................................14-19 New Coding Practices ..............................................................................................................................................................................................17-9 Special pro-STAR Features ..............................16-2 Panel definition files ........................................................................................................................................................... .................F-8 Running under IBM Loadleveler using STAR-NET ...................................F-6 Default Options ...............................F-1 Parallel Options ............................................02 ix .................. A-4 B FILE TYPES AND THEIR USAGE C PROGRAM UNITS D pro-STAR X-RESOURCES E USER INTERFACE TO MESSAGE PASSING ROUTINES F STAR RUN OPTIONS Usage ..............................................................................................F-1 Options .................................................................................................................................................. A-4 File Name Conventions ..................................................................F-11 Running under Torque using STAR-NET ...............F-12 G BIBLIOGRAPHY INDEX INDEX OF COMMANDS Version 4................................................................. 17-17 Controlling STAR ............................................................................................... A-3 Control and Function Key Conventions ................ 17-21 Scene file production and use ........... A-1 Help Text / Prompt Conventions ..........................F-8 Running under LSF using STAR-NET ..................................................... 17-15 Choosing the monitored values .F-8 Batch Runs Using STAR-NET ...............................................................................Running StarWatch .................................... 17-20 Monitoring another job ......................................................................................................................................... 17-23 APPENDICES A pro-STAR CONVENTIONS Command Input Conventions ....................................................................................................................................................................................................................................................................................F-11 Running under SGE using STAR-NET .........................F-10 Running under PBSPro using STAR-NET ...........................................................F-3 Resource Allocation ............................... 17-17 Manipulating the StarWatch display .....................................................................................................................................F-7 Cluster Computing .................................................................................................................................................... 17-21 Hard Copy Production .................................................................................................................................................................. 17-21 Neutral plot file production and use ......F-9 Running under OpenPBS using STAR-NET ................................................................................................................................ . the focus is on the structure of the system itself and how to use it. Finally. among other things. a summary of the problem specification and monitoring information generated during the calculation. Chapter 2 outlines the basic features of STAR-CD. However. to meet a user’s individual requirements. Contents Chapter 1 introduces some of the fundamental principles of computational continuum mechanics. where appropriate. etc. Chapters 3 to 5 provide the reader with detailed instructions on how to use some of the basic code facilities. Chapters 2 to 5 should be read at least once to gain an understanding of the general housekeeping principles of pro-STAR and to help with any problems arising from routine operations. Chapter 17 covers some of the less commonly used features of STAR-CD. combustion processes. Version 4. The description covers all facilities (other than mesh generation) that might be employed for modelling most common continuum mechanics problems.. Chapter 14 outlines the user programmability features available and provides an example FORTRAN subroutine listing implementing these features.02 1 . This presentation assumes that the reader is familiar with the background information provided in the Methodology volume. The important factors to consider at each step are mostly explained independently of the computer system used to perform the analysis.e. Chapter 15 presents the printable output produced by the code which provides. including the interaction between STAR and pro-STAR and how various system files are used. buoyancy-driven flows. including GUI facilities. in terms of user-defined panels. plus hints and tips on performing a successful simulation. including an outline of the basic steps involved in setting up and using a successful computer model. material property definition. session control and plotting utilities. rotating systems. Users interested in a particular topic should consult the appropriate section for a summary of commands or options specially designed for that purpose. Chapter 16 explains how pro-STAR can be customised. In this volume. the Meshing User Guide. and an overview of the GUI panels appropriate to each of them.OVERVIEW Purpose The Methodology volume presents the mathematical modelling practices embodied in the STAR-CD system and the numerical solution procedures employed. It is recommended that users refer to the appropriate chapter repeatedly when setting up a model for general guidance and an overview of the relevant GUI panels. All such subroutines are readily available for use and can be easily adapted to suit the model's requirements. Mesh generation itself is covered in a separate volume. etc. Chapters 6 to 13 describe additional STAR-CD capabilities relevant to models of a more specialised nature. boundary condition specification. reference is also made to the particular capabilities of the STAR-CD system.g. i. macros and keyboard function keys. e. . etc.). The success or failure of a continuum mechanics simulation depends not only on the code capabilities.g.g. or any other CFD. The necessary tasks include: • • • Planning the computational mesh (e. Users should turn to STAR-CD and proceed with the actual modelling only after the above tasks have been completed. Assess the capabilities and features of the STAR-CD code. size and distribution of cell dimensions. Looking up numerical values for appropriate physical parameters (e. viscosity. such information should be physically realistic and correctly presented to the analysis code. etc. Establish the amount of information available and its sufficiency and validity. Choosing the most suitable modelling option from what is available (e. should be treated as a tool to assist the engineer in understanding physical phenomena. 1-1 Version 4. The Basic Modelling Process The modelling process itself can be divided into four major phases.02 . CAD or CAE system.Chapter 1 COMPUTATIONAL ANALYSIS PRINCIPLES Introduction Chapter 1 COMPUTATIONAL ANALYSIS PRINCIPLES The aim of this section is to introduce the most important issues involved in setting up and solving a continuum mechanics problem using a computational continuum mechanics code.g. reference is made where appropriate to the particular capabilities of the STAR-CD system. density. specific heat. Plan the simulation strategy carefully.). etc. but also upon the input data. material properties and flow/deformation conditions based on the best available understanding of the relevant physics. such as: • • • • Geometry of the solution domain Continuum properties Boundary conditions Solution control parameters Introduction For a simulation to have any chance of success. number of cells. as follows: Phase 1 — Working out a modelling strategy This requires a precise definition of the physical system’s geometry.). combustion option. adopting a step-by-step approach to the final solution. The process of computational mechanics simulation does not usually start with the direct use of such a code. to ensure that the problem is well posed and amenable to numerical solution by the code. Although the discussion applies in principle to any such code. turbulence model. It is indeed important to recognise that STAR-CD. The essential steps to be taken prior to computational continuum mechanics (CCM) modelling are as follows: • • • • Pose the problem in physical terms. It is also assumed that the reader is familiar with the material presented in the Methodology volume. the model geometry). This initial phase of modelling is particularly important for the smooth and efficient progress of the computational simulation. Judging the progress of the run by analysing various monitoring data and solution statistics provided by STAR. etc.g. 1-2 Version 4. relaxation coefficients. Specifying the physical properties of the fluids and/or solids present in the simulation and. if dealing with a restart run. the turbulence model(s). Setting the solution parameters (e. etc. as shown in Figure 1-1. the results of a previous run.02 . finite. contiguous volume elements or cells.COMPUTATIONAL ANALYSIS PRINCIPLES Spatial description and volume discretisation Chapter 1 The user also has to balance the requirement of physical fidelity and numerical accuracy against the simulation cost and computational capabilities of his system.) and output data formats. Phase 4 — Post-processing the results using pro-STAR This involves the display and manipulation of output data created by STAR using the appropriate pro-STAR facilities. Phase 2 — Setting up the model using pro-STAR The main tasks involved at this phase are: • • • • • Creating a computational mesh to represent the solution domain (i. where relevant. Phase 3 — Performing the analysis using STAR This phase consists of: • • Reading input data created by pro-STAR and. His modelling strategy will therefore incorporate some trade-off between these two factors. Specifying the location and definition of boundaries and.e. solution variable selection. The two key components of this description are: • • The definition of the overall size and shape of the solution domain. The subdivision of the solution domain into a mesh of discrete. for unsteady problems. Writing appropriate data files as input to the analytical run of the following phase. further definition of transient boundary conditions and time steps. Spatial description and volume discretisation One of the basic steps in preparing a STAR-CD model is to describe the geometry of the problem. body forces. The remainder of this chapter discusses the elements of each modelling phase in greater detail. In STAR-CD both components of the spatial description are performed as part of the same operation.Chapter 1 COMPUTATIONAL ANALYSIS PRINCIPLES Spatial description and volume discretisation Figure 1-1 Example of solution domain subdivision into cells This process is called volume discretisation and is an essential part of solving the above equations numerically. The latter can be: • • • • A fluid and/or heat flow field fully occupying an open region of space Fluid and/or heat flowing through a porous medium Heat flowing through a solid A solid undergoing mechanical deformation Arbitrary combinations of the above conditions can also be specified within the same model. Whatever its composition. The user’s first task is therefore to decide which parts of the physical system being modelled need to be included in the solution domain and whether each part is occupied by a fluid. Solution domain definition Through its internal design and construction. as in problems involving fluid-solid heat transfer. Version 4. Physical boundaries — walls or solid obstacles of some description that serve to physically confine a fluid flow 2. in a cyclic or anticyclic fashion The purpose of symmetry and cyclic boundaries is to limit the size of the domain. and hence the computer requirements. This means that the user has to examine his system’s geometry carefully and decide exactly where the enclosing boundaries lie. by excluding regions where the solution is essentially known. The boundaries can be one of four kinds: 1.02 1-3 . but separate considerations apply to each of them. Cyclic boundaries — surfaces beyond which the problem solution repeats itself. the fundamental requirement is that the solution domain is bounded. Symmetry boundaries — axes or planes beyond which the problem solution becomes a mirror image of itself 3. setting up the finite-volume mesh. This in turn allows one to model the problem in greater detail than would have been the case otherwise. STAR-CD permits a very general and flexible definition of what constitutes a solution domain. solid or porous medium. The internal characteristics of the flow/deformation regime.02 . taken together. Notional boundaries — these are non-physical surfaces that serve to ‘close-off’ the solution domain in regions not covered by the other two types of boundary. should make up a surface that adequately represents the shape of the solution domain boundaries. the user should aim to represent accurately the following two entities: 1. by specifying an appropriate size and shape for near-boundary cells. they should be placed only where one of the following apply: (a) Flow/deformation conditions are known (b) Flow/deformation conditions can be guessed reasonably well (c) The boundary is far enough away from the region of interest for boundary condition inaccuracies to have little effect Thus. triangular facet Figure 1-2 Boundary representation by triangular facets 2. The overall external geometry of the solution domain. polyhedral shape. This process is greatly facilitated by STAR-CD because of its ability to generate cells of an arbitrary. Small inaccuracies may occur because all boundary cell faces (including rectangular faces) are composed of triangular facets. Their location is entirely up to the user’s discretion but. as shown in Figure 1-2. The latter’s external faces. The location and characterisation of boundaries is discussed further in “Boundary description” on page 1-10.COMPUTATIONAL ANALYSIS PRINCIPLES Spatial description and volume discretisation Chapter 1 4. These errors diminish as the mesh is refined. In creating a finite-volume mesh. locating this type of boundary may require some trial and error. in general. Mesh definition Creation of a lattice of finite-volume cells to represent the solution domain is normally the most time-consuming task in setting up a STAR-CD model. This is achieved by careful control of mesh spacing within the solution domain interior so that 1-4 Version 4. even when suitable automatic mesh generation procedures are available. time required per iteration or time step. Cost — a function of both the aforementioned factors.u.02 Aspect Ratio — values close to unity are preferable. Chapter 2 of the Meshing User Guide describes several methods available in STAR-CD. the user should aim at an optimum mesh arrangement which • • • employs the minimum number of cells.p. but departures from this 1-5 . to help the user achieve this goal. However. to a lesser extent. Numerical stability — this is a strong function of the degree of distortion. mesh distortion (discussed in “Mesh distortion” on page 1-5). Near-wall regions are important and a high mesh density is needed to resolve the flow in their vicinity. the user should try to observe the following guidelines: • Version 4. φ b θ a b/a = aspect ratio θ = internal angle φ = warp angle Figure 1-3 Cell shape characteristics When setting up the mesh. Mesh distortion Mesh distortion is measured in terms of three factors — aspect ratio. some of them semi-automatic. internal angle and warp angle — illustrated in Figure 1-3.Chapter 1 COMPUTATIONAL ANALYSIS PRINCIPLES Spatial description and volume discretisation the mesh is finest where the problem characteristics change most rapidly. is consistent with the accuracy requirements. exhibits the least amount of distortion. This point is discussed further in “Mesh distribution near walls” on page 1-7. Thus. Mesh spacing considerations The chief considerations governing the mesh spatial arrangement are: • • • Accuracy — primarily determined by mesh density and. through their influence on the speed of convergence and c. the user must still draw on knowledge and experience of computational fluid and solid mechanics to produce the right kind of mesh arrangement. i. uniform-velocity ‘free’ streams. the limits given above might not be stringent enough. the above limits may be exceeded in the region of • • simple flows such as. to • • ensure that the mesh density is high only where needed. wall boundary layers. However. Warp Angle — the optimum value of this angle is zero. Thus. and low elsewhere. the smaller the cells (and therefore the higher the mesh density).COMPUTATIONAL ANALYSIS PRINCIPLES Spatial description and volume discretisation Chapter 1 • • are allowed. the smaller the errors. especially those arising from non-orthogonality. Generally speaking. An illustration of some of the numerous cell shapes that may be employed is given in Figure 2-43 and Figure 2-44 of the Meshing User Guide. It is therefore advisable. for example. avoid rapid changes in cell dimensions in the direction of steep gradients in the flow variables. in regions of steep gradients of the flow variables. On the other hand. 1-6 Version 4. non-orthogonality at boundaries may cause problems and should be minimised whenever practicable. “Mesh and Geometry Checking” of the Meshing User Guide. What is really important in this respect is the combined effect of the various kinds of mesh distortion. where cells of high aspect ratio (in the flow direction) are commonly employed without difficulty. It is difficult to place rigid limits on the acceptable departures because they depend on local flow conditions. wherever possible. which can occur only when the cell face vertices are co-planar. Internal Angle — departures from 90° intersections between cell faces should be kept to a minimum. as discussed in Chapter 3. The flexibility afforded by STAR-CD’s unstructured polyhedral meshes facilitates such selective refinement. However. with associated high computing cost. the effects of distortion also depend on the nature of the local flow.02 .e. and the signs of the coefficients (negative values are generally detrimental). Any adverse effects arising from departures from the preferred values of these factors manifest themselves through • • the relative magnitudes of the coefficients in the finite-volume equations. If all three are simultaneously present in a single cell. a high mesh density implies a large number of mesh storage locations. the following values serve as a useful guideline: Aspect Ratio Internal angle Warp angle 10 45° 45° pro-STAR can calculate these quantities and identify cells having out-of-bounds values. Mesh distribution and density Numerical discretisation errors are functions of the cell size. Note that the above considerations apply to Reynolds Stress models as well as several classes of eddy viscosity model (see Chapter 3. and hence the thickness of that layer. this distance must be • • not too small. otherwise. is usually determined by reference to the dimensionless normal distance y + from the wall.02 1-7 . These functions effectively allow the boundary layer to be bridged by a single cell. as the flow at that location might not behave in the way assumed in deriving the wall functions. it is not always possible to ascertain a priori what the flow structure will be. not too large. Outer region y (a) Wall function model Inner region (b) Two-layer or Low Re models Figure 1-4 Near-wall mesh distribution The location y of the cell centroids in the near-wall layer. Alternative treatments that do not require the use of wall functions are also available. the ‘bridge’ might span only the laminar sublayer. the need for higher mesh density can usually be anticipated in regions such as: • • • • • • Wall boundary layers Jets issuing from apertures Shear layers formed by flow separation or neighbouring streams of different velocities Stagnation points produced by flow impingement Wakes behind bluff bodies Temperature or concentration fronts arising from mixing or chemical reaction Mesh distribution near walls As discussed in Chapter 6. These are: Version 4. “Wall Boundary Conditions” of the Methodology volume. However. For the wall function to be effective. as shown in Figure 1-4(a). Ideally. “Turbulence Modelling”). wall functions are an economic way of representing turbulent boundary layers (hydrodynamic and thermal) in turbulent flow calculations.Chapter 1 COMPUTATIONAL ANALYSIS PRINCIPLES Spatial description and volume discretisation Of course. y + should lie in the approximate range 30 to 150. the solution domain should be divided into two regions with the following characteristics: • • An inner region containing a fine mesh An outer region containing normal mesh sizes The two regions are illustrated in Figure 1-4(b). Chapter 15 (“Internal Sliding Mesh” on page 15-5 and “Cell Layer Removal and Addition” on page 15-7). The user must therefore ensure that the problem is well defined in respect of: • • • • 1-8 The nature of the fluid flow (e. These are summarised in the Methodology volume. viscosity. Moving mesh features STAR-CD offers a range of moving mesh features. called the hybrid wall function is also available that extends the low-Reynolds number formulation of most turbulence models. density. or indeed to obtaining any solution at all. including: • • • General mesh motion Internal sliding mesh Cell deletion and insertion The first of these is straightforward to employ and the only caution required is the obvious one: avoid creating excessive distortion when redistributing the mesh. This caution also applies to the use of the other two features. incompressible/compressible) Physical properties (e. gravity. A more recent development. specific heat) External force fields (e. steady/unsteady.g. Problem characterisation and material property definition Correct definition of the physical conditions and the properties of the materials involved is a prerequisite to obtaining the right solution to a problem. Two-layer turbulence models. whereby wall functions are replaced by a one-equation k-l model or a zero-equation mixing-length model 2. Additional guidelines also appear in this volume. Low Reynolds number models (including the V2F model). the inner region should contain at least 15 mesh layers and encompass that part of the boundary layer influenced by viscous effects. “Two-layer models”).g.COMPUTATIONAL ANALYSIS PRINCIPLES Problem characterisation and material property definition Chapter 1 1.g.02 . As explained in the Methodology volume (Chapter 6. laminar/turbulent. hence they are not repeated here. but they have additional rules and guidelines attached to them. when present Initial conditions for transient flows Version 4. centrifugal forces) and energy sources. where viscous effects are incorporated in the k and ε transport equations For the above two types of model. “Cell-layer Removal/Addition” on page 12-14 and “Sliding Meshes” on page 12-18. It is also essential for determining whether the problem can be modelled with STAR-CD. This may be used to capture boundary layer properties more accurately in cases where the near-wall cell size is not adapted for the low-Reynolds number treatment and thus achieve y + independent solutions. In such cases. thermal conductivity. it is important to understand the physical implications and avoid specifying conditions that lead to Version 4. When required. For example. • Force fields and energy sources As already noted. user-programmable functions may be used. molecular viscosity.02 1-9 . None of them can represent transitional behaviour accurately. STAR-CD contains several built-in equations of state from which density can be calculated as a function of one or more of the following field variables: • • • Pressure Temperature Fluid composition In all cases where complex calculations are used to evaluate a material property. It is also possible to insert additional. STAR-CD has built-in provision for body forces arising from • • buoyancy. It is important to remember that as the strength of the body forces increases relative to the viscous (or turbulent) stresses. Problems will arise if an incorrect choice is made. the following measures are recommended: • • • The relevant field variables must be assigned plausible initial and boundary values. rotation. In these circumstances it is advisable to switch to the transient solution mode.Chapter 1 COMPUTATIONAL ANALYSIS PRINCIPLES Problem characterisation and material property definition Nature of the flow It is very important to understand the nature of the flow being analysed in order to select the appropriate mathematical models and numerical solution algorithms. such as vortex shedding from a bluff body Computing a turbulent flow without invoking a suitable turbulence model Modelling transitional flow with one of the turbulence models currently implemented in STAR-CD. external force fields and energy sources via the user programming facilities of STAR-CD. “Scalar transport equations”). the user should consider under-relaxation of the property value calculations. Physical properties The specification of physical properties. STAR-CD’s facility for alternative. as in the following examples: • • • Employing an iterative. etc. steady-state algorithm for an inherently unsteady problem. In the case of strong dependencies between properties and field variables. properties should be solved for together with the field variables as part of the overall solution. in the manner described in the Methodology volume (Chapter 7. the flow may become physically unstable. Where necessary. such as density. depends on the nature of the fluids or solids involved and the circumstances of use. Due care must therefore be taken in providing it. • Poor initial field specifications or. since the boundary topography is defined by the outermost cell faces. flows that are temporally periodic). Examples of such conditions are: • • Thermal energy sources that increase linearly with temperature. the following special ‘start-up’ measures may be necessary to ensure numerical stability: • • Use of unusually small time steps in transient calculations. this information has a clear physical significance and will affect the course of the solution. the initial conditions will usually have no influence on the final solution (apart from rare occasions when the solution is multi-valued). Furthermore. Initial conditions The term ‘initial conditions’ refers to values assigned to the dependent variables at all mesh points before the start of the calculations. abrupt changes in boundary conditions put severe demands on the numerical algorithm when substituted into the finite-volume equations. It sometimes happens that the effects of initial conditions are confined to a start-up phase that is not of interest (as in. the result may be numerical instability whereby small pressure perturbations produce a large change in velocities. for transient problems.02 . Boundary description As stated in “Spatial description and volume discretisation” on page 1-2. These can give rise to physical instability called ‘thermal runaway’. However. In either case. Specific recommendations concerning these practices are given in “Numerical solution control” on page 1-13. In calculating steady state problems by iterative means. but may well determine the success and speed of achieving it. Setting the coefficient β i in the permeability function K i = α i v + β i to a very small or zero value.COMPUTATIONAL ANALYSIS PRINCIPLES Boundary description Chapter 1 physical or numerical instability. correct specification of the boundary conditions is often the main area of difficulty in setting up a model. Their implication depends on the type of problem being considered: • In unsteady applications. As a consequence. for example. Problems often arise in the following areas: • • • Identifying the correct type of condition Specifying an acceptable mix of boundary types Ascribing appropriate boundary values The above are in turn linked to the decisions on where to place the boundaries in the 1-10 Version 4. boundary identification and description are intimately connected with the generation of the finite-volume mesh. Use of strong under-relaxation in iterative solutions. it is still advisable to take some precautions in specifying initial conditions for reasons explained below. If the local fluid velocity also becomes very small. increased computing times can be an undesirable side effect. 3. (b) Ensure that. are to place boundaries • • • in regions where the conditions are known. Outlet — The main points to note for this boundary type are: (a) The need to specify the boundary. where possible. Boundary conditions Another source of potential difficulty is in boundary value specification wherever known conditions need to be set.Chapter 1 COMPUTATIONAL ANALYSIS PRINCIPLES Boundary description first instance. (b) Prescribed flow split outlets coexisting with prescribed mass outflow boundaries in the same domain. A boundary that passes through a major recirculation zone. A mix of boundary conditions that is inappropriate. if inflow Version 4. to numerical instability The following recommendations can be given regarding each different type of boundary: 1. an outlet boundary located where the flow is not supersonic. if this is possible. 2. In transient transonic or supersonic compressible flows. The basic points to bear in mind in this situation are: • • All transport equations to be solved require specification of their boundary values. Whenever possible. Prescribed flow — Here. in a location where the ‘Outlet’ or ‘Prescribed Pressure’ option is applicable (see Chapter 5 in the Methodology volume). for example at outlets. in decreasing degree of accuracy. where the approximations in the boundary condition specification are unlikely to propagate upstream into the regions of interest. such as density. including the turbulence parameters. Examples of this are: (a) Multiple ‘Outlet’ boundaries — unless further information is supplied on how the flow is partitioned between the outlets. at locations where the flow is everywhere outwardly directed. in extreme cases. if this is the only type of flow boundary imposed. Boundary location Difficulties in specifying boundary location normally arise where the flow conditions are incompletely known.02 1-11 . e. care should be taken to: (a) Assign realistic values to all dependent variables. also to recognise that. including the turbulence transport equations when they are invoked Inappropriate setting of boundary values leads to erroneous results and. and also to auxiliary quantities. it is particularly important to avoid the following situations: 1. An error message is issued if the imbalance exceeds this figure). The recommended solutions. overall continuity is satisfied (STAR-CD will accept inadvertent mass imbalances of up to 5%.g. 2. correcting them by adjusting the outflows. (c) A combination of prescribed pressure and flow-split outlet conditions. at a ‘Prescribed Inflow’ or ‘Inlet’ boundary. make use of the CD/UD blending scheme to apply the maximum level of central differencing in the tangential direction (the default blending factor is 0. (b) For axisymmetric flows. Stagnation conditions — It is recommended to use this condition for boundaries lying within large reservoirs where properties are not significantly affected by flow conditions in the solution domain.02 . Transient wave transmissive boundaries — Used only in problems involving transient compressible flows 10.95. (b) If inflow is likely to occur. 4. Planes of symmetry — It is recommended to use this condition for two-dimensional axisymmetric flows without swirl 8. (c) The inapplicability of ‘prescribed split’ outlets to problems where the inflows are not fixed. Cyclic boundaries — These always occur in pairs. e. Two-dimensional axisymmetric flows with swirl is a good example of an appropriate application. 7. see also on-line Help topic “Miscellaneous Controls” in STAR GUIde).g. of prescribing either the flow split between them or the mass outflow rate at each location. to assign realistic boundary values to temperature and species mass fractions. Riemann boundaries — This condition is based on the theory of Riemann invariants and its application allows pressure waves to leave the solution domain without reflection 1-12 Version 4. Free-stream transmissive boundaries — Used only for modelling supersonic free streams 9. it may introduce numerical instability and/or inaccuracies. or ii) in the case of transient compressible flows. (b) The necessity. 3. Prescribed pressure — The main precautions are: (a) To specify relative (to a prescribed datum) rather than absolute pressures. It is also advisable to specify the turbulence parameters indirectly. The main points of advice are: (a) Impose this condition only in appropriate circumstances. 5. i) in combination with pressure boundary conditions. via the turbulence intensity and length scale or by extrapolating them from values in the interior of the solution domain. developed to facilitate analysis of steady-state turbomachinery applications 6.COMPUTATIONAL ANALYSIS PRINCIPLES Boundary description Chapter 1 occurs. if more than one boundary of this type is declared. Non-reflecting pressure and stagnation conditions — A special formulation of the standard pressure and stagnation conditions. according to prescribed tolerances and upper limits. Thus. starting from well-defined initial and boundary conditions and proceeding to a new state in a series of discrete time steps. during which linear equation sets are solved iteratively for each main dependent variable. In most other transient flow problems. The decisions on the number of correctors and inner iterations (hereafter referred to as ‘sweeps’. SIMPLE is the default algorithm for steady-state solutions and works well in most cases. where an unchanging flow/deformation pattern under a given set of boundary conditions is arrived at through a number of numerical iterations. When doubts exist as to whether the problem considered actually possesses a steady-state solution or when iterative convergence is difficult to achieve. Selection of solution procedure The basic selection should be based on a correct assessment of the nature of the problem and will be either • • a transient calculation. a predictor. Transient flow calculations with PISO As stated in “The PISO algorithm” on page 7-2 of the Methodology volume. In such cases. the means of controlling the process depend heavily on the particular numerical techniques employed so no universal guidelines can be given. both for acceptable computational efficiency and. deposition of chemical species on walls in after-treatment of exhaust gases. PISO is the default for unsteady calculations and is sometimes preferred for steady-state ones. it is better to perform the calculations using the transient option.). transient SIMPLE can be used to save on computing time. in order to achieve a solution at all. where it is the only option. or a steady-state calculation. there are situations in which PISO would require many correctors or even fail to converge unless the time step is reduced. By necessity. in cases involving strong coupling between dependent variables such as buoyancy driven flows. This is the case when the flow changes very little but certain slow transients are present in the behaviour of scalar variables (e. followed by a number of correctors. etc. to avoid confusion with outer iterations performed as part of the steady-state solution mode) are made internally on the basis of the splitting error and inner residual levels.02 1-13 .g. PISO performs at each time (or iteration) step. SIMPLE is also used for transient calculations in the case of free surface and cavitating flows. respectively. PISO and SIMPLE are the two alternative solution procedures available in STAR-CD. the recommended settings vary with the particular algorithm selected and the circumstances of application. whereas SIMPLE may allow larger time steps with a moderate number of outer iterations per time step. However. slow heating up of solid structures in the case of solid-fluid heat transfer problems. PISO is likely to be more efficient due to the fact that PISO correctors are usually cheaper than outer iterations on all variables within a time step of the transient SIMPLE algorithm. sometimes. The default values for the solver tolerances and Version 4.Chapter 1 COMPUTATIONAL ANALYSIS PRINCIPLES Numerical solution control Numerical solution control Proper control of the numerical solution process applied to the transport equations is highly important. Again. twofold changes are appropriate. then this should be tried. Corrector step tolerance — this may be set to a lower value but consult Version 4. it is possible to operate with δ t ≈ 50 δ t c and still obtain reasonable temporal accuracy. and δ L is a mean mesh dimension.01 100 Mass fraction 0. Normally. The step should ideally be of the same order of magnitude as the smallest characteristic time δ t c for convection and diffusion. i. During the course of a calculation.e. in which case messages to this effect will be produced. for severe mesh distortion or flows with Mach numbers approaching 1).0 Corrector limit = 20 Corrector step tolerance = 0. an initial factor of 2 — if this improves matters. ---------- ----Γ  U   2 (1-1) Here. This is normally determined by accuracy considerations and may be varied during the course of the calculation. Pressure under-relaxation — a value of 0. these will only require adjustment by the user in exceptional circumstances.01 100 Pressure 0. the limits given in Table 1-1 may be reached. If. respectively. This is most likely to occur during the start-up phase but is nevertheless acceptable if. and the predictions look reasonable.01 100 Pressure under-relaxation factor = 1. U and Γ are a characteristic velocity and diffusivity.01 100 Enthalpy 0.8 for pressure correction under-relaxation. later on. then the cause may simply be an excessively large δ t . however.COMPUTATIONAL ANALYSIS PRINCIPLES Numerical solution control Chapter 1 maximum correctors and sweeps are given in Table 1-1. δ L ρδ L  δ t c = min  -. may be helpful for some difficult cases (e.02 • • 1-14 . The possible actions are: • • Reduction in time step by. say. the warnings persist.25 The remaining key parameter in transient calculations with PISO is the size of the time increment δ t . only on the variable(s) whose limit(s) have been reached. Typically. the warnings either cease entirely or only appear occasionally. Table 1-1: Standard Control Parameter Settings for Transient PISO Calculations Variable Parameter Velocity Solver tolerance Sweep limit 0.g. Values significantly above this may lead to errors and numerical instability. using PISO. whereas smaller values will lead to increased computing times. Increase in the sweep limits — if measure 1 fails. as discussed below.001 1000 Turbulence 0. corrective actions should be taken. the inner residual tolerances are decreased and under-relaxation is introduced on all variables.g.05 1000 1. then it may be worthwhile increasing the limit(s) on the offending variables. The main remedies now available are: • Reduction in relaxation factor(s) — this should be done in decrements of between 0. 1-15 • • • Version 4. The standard.1 100 0. the last two variables may need to be under-relaxed for buoyancy driven problems. the offending variable(s) can be identified from the behaviour of the global residuals. which are unchanged from the transient mode. and mixing of dissimilar gases. default values for these parameters and the sweep limits. especially in respect of the pressure tolerance and its importance to the flow solution.10 and should be applied to the velocities if the momentum and/or mass residuals are at fault. all being well.1 100 0.05 and 0.02 . then remedial measures will be necessary. depending on mesh density and other factors.1 100 0.7 Pressure 0.0 Turbulence 0.0 Corrector limit = 20 Corrector step tolerance = 0. compressible flows.7 Enthalpy 0. combustion. In some instances. If. this may prove beneficial. . Under-relaxation of density and effective viscosity — use of this method for density can be advantageous where significant variations occur. Decrease in solver tolerances — as in the transient case. Steady-state flow calculations with PISO When PISO operates in this mode. result in near-monotonic decrease in the global residuals during the course of the calculations. e. Increase in sweep limits — if warning messages about the limits being reached appear and are not suppressed by measures 1 and 2. Effective viscosity oscillations can arise in turbulent flow and non-Newtonian fluid flow and can be similarly damped by this device. one or more of the global residuals R φ do not fall. thereafter.1 100 1. apart from pressure.25 These settings should. temperature and mass fraction. However.95 Mass fraction 0. are given in Table 1-2. A twofold reduction should indicate whether this measure will work.Chapter 1 COMPUTATIONAL ANALYSIS PRINCIPLES Numerical solution control CD adapco first. Table 1-2: Standard Control Parameter Settings for Steady PISO Calculations Variable Parameter Velocity Solver tolerance Sweep limit Relaxation factor 0. given in the previous section.8 if the velocity factor is low. 0. When many similar problems need to be solved. a substantial reduction of the under-relaxation factor for velocities and turbulence model variables should be tried (e. or from highly complex physics (many variables affecting each other). If this does not help. The problems usually arise either from a highly distorted mesh. reduction of the pressure relaxation factor is an additional device for overcoming convergence problems. it is worth trying to work near the optimum as this may save a lot of computing time. Usually. the control parameters available for SIMPLE are similar to those for PISO. On the other hand. say around 0. Note that the pressure under-relaxation factor needs to be adjusted within the limits of some range to make the iteration process converge. but outside this range the iterative process would diverge. e.95 Mass fraction 0. this range becomes narrower when the mesh is distorted.0 . in the case of the former. the one for pressure can be varied within some range without affecting the total number of iterations and computing time.02 . the problem may lie in severe mesh defects or errors in the set-up. for a given velocity relaxation factor. a single corrector stage is always used and pressure is under-relaxed. Table 1-3: Standard Control Parameter Settings for Steady SIMPLE Calculations Variable Parameter Velocity Solver tolerance Sweep limit Relaxation factor 0. the wider the range of pressure relaxation factors that can be used (e.7 Enthalpy 0.1 100 0.relaxation factor for velocities).g.1 100 1.g. . the relaxation factor for pressure can be selected as (1.05 1000 0.COMPUTATIONAL ANALYSIS PRINCIPLES Numerical solution control Chapter 1 Steady-state flow calculations with SIMPLE As noted previously.1 100 0.2 for pressure and 0. improving the mesh quality can be of much greater help. here.5). to 0.g. The limit to which the velocity relaxation factor can be increased is both problem. where the number of iterations required to reach such convergence is mainly dictated by the corresponding factors for velocities (and for scalar variables when strongly coupled to the flow). between 0.8 for velocities.7 Pressure 0.1). to 0. The lower the relaxation factor for velocities. except that. then the measures to be taken are essentially the same as those for iterative PISO.and mesh-dependent.5). The standard (default) settings are given in Table 1-3.05 and 0. Further reduction of under-relaxation factors may be tried if the grid is severely distorted and cannot be improved. 1-16 Version 4. one should reduce the relaxation factor for pressure from the beginning of the run (e.1 100 0.0 In the event of failure to obtain solutions with the standard values.g. However.3 Turbulence 0. otherwise. In the case of well-behaved flows and reasonable meshes. If convergence problems are still encountered. If the grid is distorted. Table 1-4: Standard Control Parameter Settings for Transient SIMPLE Calculations Variable Parameter Velocity Solver tolerance Sweep limit Relaxation factor 0. by recalculating the coefficient matrix and source term.1.) can be averaged over several oscillation periods. the larger the values that can be used for relaxation factors — 0.3 Turbulence 0. since the discretization of the transient term enlarges the central coefficient of the matrix in the same way as under-relaxation does. The default control parameter settings are therefore as summarised in Table 1-4. lift.7 Enthalpy 0.0 Mass fraction 0. solver tolerances do not need to be as tight as for PISO.05 1000 0. they are actually identical to those used for steady-state computations.9 Pressure 0. the relaxation factors for velocities and scalar variables can be increased (the smaller the time step.0 Outer iteration limit = 5 The main difference compared to the PISO algorithm lies in the fact that all linearizations and deferred correctors are updated within the outer iterations. a transient simulation should be performed. . pressure drop. in which case the quantities of interest (drag. heat transfer coefficient.1 100 0. This is often the case when the problem geometry possesses some form of symmetry but the Reynolds (or another equivalent) number is high and recirculation zones are present. However. Transient flow calculations with SIMPLE The use of this algorithm in transient calculations essentially consists of repeating the steady-state SIMPLE calculations for each prescribed time step. it may be more efficient to use a conservative setting. a steady-state solution cannot be achieved due to the inherent unsteady character of the flow.1 100 0. Note that under some conditions.95 or even more).1 100 1. such as those in Tutorial 13. for an one-off analysis. The “solution” at that stage may be far from a valid solution of the governing equations and should not be interpreted as such unless the residual level is sufficiently small.02 1-17 . In such cases. etc. while a less diffusive turbulence model (such as Reynolds Stress and non-linear eddy-viscosity models) combined with a higher-order differencing scheme (such as central differencing) may not. the unsteady solution may oscillate around a mean steady state.Chapter 1 COMPUTATIONAL ANALYSIS PRINCIPLES Numerical solution control On the other hand. For this reason. In this case the residuals stop falling at some level and then continue to oscillate.1 100 1. The convergence criterion for outer iterations within each time step is by default Version 4. An eddy-viscosity turbulence model (such as the standard k-e) combined with a first-order upwind scheme for convective fluxes may produce a steady-state solution. this is a sign that the time step is too large. it is necessary to select smaller time steps in the initial phase of a transient simulation than those at later stages. Instructions on how to do this are provided in the Installation Manual. The transient SIMPLE algorithm allows you to select either the default fully-implicit Euler scheme or the three-time-level scheme for temporal discretisation. provided that the residuals of all other equations have satisfied the criterion. They usually manifest themselves as failure of the iterative solvers to converge or. however. if residuals drop below the limit after only a few iterations. in divergence leading to machine overflow. As a general rule. in extreme cases. when starting with a fluid at rest and imposing a full-flow rate at the inlet. but problems can sometimes arise when operating in single precision on 32-bit machines. which would also require that the time step be reduced.02 . the existence of very small cells. if substantially more iterations are needed to satisfy the convergence criterion. a linear increase of velocity from zero to full speed over some period of time).).g. Sometimes.g. the mass residuals are more than an order of magnitude lower. In some cases. Alternatively.COMPUTATIONAL ANALYSIS PRINCIPLES Numerical solution control Chapter 1 the same as for steady-state flows. you should try to avoid generating very small values for cell volumes and cell face areas by working with sensible length units. it may prove useful to invest some time in optimizing the relaxation parameters. This is the case. It should be chosen when temporal variation of the velocity field is essential. All these considerations are of course problemdependent and if several simulations over a longer period need to be performed. If difficulties are encountered with problems of this kind. transient SIMPLE may allow the use of larger time steps than PISO without loss of accuracy. poor mesh quality etc. This is equivalent to a sudden change of boundary conditions at a later time. one may increase the time step. On the other hand. For this reason.g. Another possibility of avoiding problems with abrupt starts from rest is to ramp the boundary conditions (e. However. in the case of a DES/LES type of analysis. e. described in Chapter 4.8) can lead to a faster reduction of mass residuals. In such a case. “Temporal Discretisation” of the Methodology volume. you could re-specify your 1-18 Version 4. experience shows that optimum efficiency and accuracy are achieved if 5 to 10 outer iterations per time step are performed. one can accept mass residuals being somewhat higher than the convergence criterion when the limiting number of outer iterations is reached. after this equation is solved and mass fluxes are corrected. While PISO would normally be the preferred choice for the latter. the number of outer iterations is also set to a default limit of 10. The latter scheme is second-order accurate but is currently applied only to the momentum and continuity equations. Effect of round-off errors Efforts have been made to minimise the susceptibility of STAR-CD to the effects of machine round-off errors. then it is clearly advisable to switch to double precision calculations. Note also that the reported mass residuals are computed before solving the pressure-correction equation. for example. an increase in the under-relaxation factor for pressure (up to 0. because this would lead to a more accurate solution at a comparable cost. under some circumstances (e. it is better to reduce the time step rather than allow more outer iterations for a larger time step. or full speed of rotation (in the absence of a better initial condition). especially for steady-state calculations. Apart from turbulence dissipation rate residuals (see Chapter 7. the non-linearities and interdependencies of the equations may result in non-monotonic decrease of the residuals. for two reasons: 1. These quantities provide a direct measure of the degree of convergence of the individual equation sets and are therefore useful both for termination tests and for identifying problem areas when convergence is not being achieved. “Completion tests” in the Methodology volume) may not be appropriate for the application.Chapter 1 COMPUTATIONAL ANALYSIS PRINCIPLES Monitoring the calculations problem geometry units while preserving relevant non-dimensional quantities such as Re and Gr. Choice of the linear equation solver STAR-CD offers two types of preconditioning of its conjugate gradient linear equations solvers: one which vectorises fully. the first one (called ‘vector’ solver) is recommended when the code is run on vector machines (such as Fujitsu and Hitachi computers). “Completion tests” in the Methodology volume). this may be indicative of problems. Version 4. 2. This consists of: • Values of all dependent variables at a user-specified monitoring location. Monitoring the calculations Chapter 5 and the section on “Permanent Output” on page 15-1 give details of the information extracted from the calculations at each iteration or time step and used for monitoring and control purposes. which is numerically superior to the first one but vectorises only partially. and the second one (called ‘scalar’ solver) is recommended if the code is run on scalar machines (such as workstations). 50 iterations. e. Ideally. The normalisation practices used (see Chapter 7. it should be in a sensitive region of the flow where the approach to the steady state is likely to be slowest. and the other. The normalised global residuals R φ for all equations solved. For example. Therefore.g. a location may be chosen so as to confirm an expected periodic behaviour in the flow variables. Care should be taken in the choice of location. In the early stages of a calculation. In transient flow calculations. a zone of recirculation. the information has a different significance and other criteria for choice of location may apply. It follows from the above discussion that strong reliance is placed on the global residuals to judge the progress and completion of iterative calculations of steady flows. say. It is also necessary that the features of interest in the solution should have stabilised to an acceptable degree. it is advisable to reduce the tolerance and continue the calculations. If these oscillations persist after.02 1-19 . • Remember that reduction of the normalised residuals to the prescribed tolerance (λ) is a necessary but not sufficient condition for convergence. these are used to judge the progress and completion of iterative calculations for steady and pseudo-transient solutions. If doubts exist in either respect. 4. Interpolated values of the above quantities at arbitrary. More complete information on specified boundary values can be obtained from the screen printout. This can be checked visually by using the built-in colour differentiation scheme. Version 4. Boundary conditions are correct. The initial conditions should also be checked. 3. Briefly. by producing special mesh views that show (a) boundary location. particularly for transient problems and initial fields specified through user subroutines. inlet velocities). Alternatively. each material’s mesh domain can be plotted individually. This is greatly facilitated by the built-in graphics capabilities that allow the mesh display to be (a) (b) (c) (d) rotated. with the view showing the correct three-dimensional perspective. printouts and/or plots can be produced of the following: • • Field values of all primary variables at interior and boundary nodes. In performing the modelling stages discussed previously. Materials of different physical properties occupy the correct location in the mesh. particularly for complex-geometry problems. Frequent mesh displays during the mesh generation stage are very useful for verifying the accuracy of what is being created and are therefore strongly recommended. the next task is to run the STAR-CD solver and check the results of the numerical calculations. Checking the calculations Having completed the model preparation. (b) boundary type. details of which are given in the Post-Processing User Guide.g. (c) a schematic of the conditions applied (e. reduced. Precise values of specified properties can be checked via the screen printout. These results are presented in various ways. user-specified points or surfaces within the solution domain.02 1-20 . It is best if such geometries are subdivided into convenient parts that can be individually meshed and then checked visually. enlarged. The mesh geometry agrees with what it is supposed to represent. This enables the user to look at the mesh from any viewpoint. displaced. 2.COMPUTATIONAL ANALYSIS PRINCIPLES Model evaluation Chapter 1 Model evaluation Checking the model STAR-CD offers a variety of tools to help assess the accuracy and effectiveness of all aspects of the model building process. by running the STAR-CD solver for zero iterations/time steps and plotting the relevant field variables. the user should therefore take advantage of these facilities and check that: 1. if necessary. especially for three-dimensional problems involving complex geometries. this approach may not be feasible. temporal) is assessed and arrangements made for their reduction to acceptable levels. for it is not possible to achieve it by a simple calculation.g. these should be done independently) and noting regions of appreciable change in the solution. It is important to examine this information carefully to verify that the calculations have been properly set up and are producing sensible results. drag. also values of the dimensionless coordinate y+ for near-wall mesh nodes. due to the large preparation and computing overheads. the user should ensure that: • • The interior fields are examined for plausibility and similar checks made on global quantities. available in STAR-CD will usually produce the lowest numerical errors. What is required are the following: • A reliable means of evaluating the discretisation errors. the last is currently the most difficult. or blends thereof. At present. In the case of calculations with a two-layer model. Strategies for altering the mesh or time step to reduce errors. The magnitude of numerical discretisation errors (spatial and. checks should be made that the mesh is sufficiently dense within the near-wall layer.02 1-21 . the near-wall node y+ values are within the recommended range (30-100) in regions where adherence to this constraint is important. where relevant. lift) on submerged bodies and their dimensionless counterparts. These adjustments are made manually. • Of the above tasks. Version 4. For turbulent flow calculations. The second-order options. the error correction process should continue until the changes fall to acceptable levels. In particular. etc. overall energy balances. An alternative way of gaining some insight into the presence of spatial truncation errors is to change the spatial discretisation scheme and note the effect on the solution. Global quantities such as total force components (e. this is accomplished by repeating the calculations with finer meshes and smaller time steps (strictly. • Ideally. In practice.Chapter 1 COMPUTATIONAL ANALYSIS PRINCIPLES Model evaluation • • Surface heat and mass transfer coefficients and forces. . Graphical tools such as drop-down menus. All aspects of user interaction are handled by pro-STAR. draw sophisticated 3-D graphical images. initial conditions. Version 4. analysis controls. manipulate the data read in. animate those images.Chapter 2 BASIC STAR-CD FEATURES Introduction Chapter 2 BASIC STAR-CD FEATURES The main aim of this part of the manual is to provide users. summarise information on the calculated results. Linux or Windows implementations of STAR-CD using the OSF Motif graphics environment. fluid and solid material properties. whether experienced or not in the application of general-purpose computational continuum mechanics codes. pro-STAR is a combined command-. and process panel-driven program. pro-STAR can • • • • • • • read and re-format the various data files produced by the analysis. menu-. sliders. The choice of working interface is entirely up to the user and depends on • • • whether the available terminal can accept and display graphical input and output. GUI facilities are available for UNIX. push-buttons. expected to have gone through Chapter 1 and the material in the Methodology volume. pro-STAR is the means by which the user defines the • • • • • • geometry. boundary conditions. They consist of two basic types: 1. enabling rapid visualisation of even the largest models. As a pre-processor. Their purpose and best way of using them are explained throughout this volume. dialog boxes. calculation mesh. produce extensive and easily comprehensible printouts. with advice on effective ways of setting up and running a basic continuum mechanics model using STAR-CD. Both pre. etc. however. user preference and level of experience with STAR-CD. or have their starting point located somewhere on that window. The reader is. plus on-line context sensitive help that provides detailed information on usage.and post-processing subsystem of the STAR-CD suite. graphical user interface (GUI) environment. As a post-processor.and post-processing operations are served by an extensive set of plotting facilities. Introduction which uniquely determine the problem to be solved.02 2-1 . the pre. to assist users in specifying the desired pro-STAR actions. whether the host computer’s operating system supports a windowed. These facilities are arranged around the main pro-STAR window. draw graphs of various calculated quantities. • • • Running a STAR-CD Analysis A STAR-CD analysis may be performed in one of the following two ways: • By typing a series of script names in a shell or command prompt. For the convenience of users who prefer to work with commands. Tools are selected as necessary. Users can greatly influence the speed with which certain operations are performed by intelligent use of the available options. the description of every GUI panel and dialog box also includes a list of commands that have equivalent functionality. An outline description is given in the section entitled “The STAR GUIde Environment” on page 2-38. By employing a new utility. as an aid to navigating through the various STAR-CD functions. STAR-Launch. the same principles of use apply. This method should be particularly beneficial to novice users. that: • In the present release. Note. These represent an additional GUI facility. the discussion is in terms of commands rather than GUI operations. each of them represented by a menu-item choice. A summary of all pro-STAR commands is given in Appendix B of the Commands volume.02 • 2-2 . A series of process-oriented panels contained within the STAR GUIde window. A tool always provides instant feedback so the user can tell immediately if it was used properly. “The Basic Modelling Process” and is further elaborated in the Tutorials volume. The same information is also available on line by choosing Help > pro-STAR Help from the menu bar in the main pro-STAR window and then selecting item PROGRAM (for command syntax) or COMLIST (for command summary) in the scroll list at the bottom of the Help dialog box. This is the original method of working with STAR-CD and. each designed to help you build a CFD model. Information on how to use this environment is provided by an on-line Help system accessed from within the STAR GUIde window. The recommended sequence is described in Chapter 1. however. Where this is the case. a number of pro-STAR facilities are not accessible via either of the GUI systems. namely: • A model is constructed or examined with the aid of numerous functions or ‘tools’. obtain a solution and then display the analysis results. a special dialog box.BASIC STAR-CD FEATURES Running a STAR-CD Analysis Chapter 2 2. in a sequence that is sensible for modelling purposes. A summary of pro-STAR’s conventions regarding command syntax can be found in this volume. Details of all available commands and specific aspects of the command-driven mode of operation are discussed in the Commands volume. suitable for building STAR-CD models from scratch. a STAR GUIde panel or a command. • • Whichever operating mode is chosen. Version 4. may be the quickest way of getting results. for reasonably experienced users. Appendix A. 02 .e. The desired pro-STAR setup is defined by a number of environment variables such as: STARUSR — path to the location of files PRODEFS (for command abbreviations) and PROINIT (for pro-STAR initialisation) — see Chapter 16. supplied with the STAR-CD installation CD-ROM. Note that these settings can usually be made once and for all. “Macros”) PANEL_LOCAL and PANEL_GLOBAL — paths to the local and global user-defined panel locations (see Chapter 16. Step 2 Create a separate subdirectory for each case to be analysed and give it a descriptive name. Step 3 Move to the appropriate subdirectory and start a pre-processing (model building) session by typing: prostar The system will respond by prompting you to define the pro-STAR variant you wish to use Please enter the required graphics driver Available drivers are: x. This helps to organise the various files created during a run and makes it much easier to check or repeat previous work. at the time when STAR-CD is first installed on your computer. the procedure described below should be followed in the order indicated: Step 1 Set up an appropriate environment for your STAR-CD system. “Set-up Files” MACRO_LOCAL and MACRO_GLOBAL — paths to the local and global macro locations (see Chapter 16. “Panel definition files”) TMPDIR — path to the location of pro-STAR’s temporary (scratch) files Further instructions on how to set the STAR-CD environment variables are given in the Installation and Systems Guide.Chapter 2 BASIC STAR-CD FEATURES Running a STAR-CD Analysis Using the script-based procedure To perform the analysis using scripts. mesa [xm] where the options refer to the various types of graphics libraries commonly used for graphical displays in workstations or X-terminals. x xm glm mesa — — — — X-windows X-windows using the Motif interface for pro-STAR’s GUI functions Motif interface plus the standard OpenGL libraries for pro-STAR’s GUI functions As above but using the Mesa OpenGL library (this option is not available in Windows ports) 2-3 Version 4. xm. i. glm. These should include: • • File . containing a full description of the model geometry. This may be overridden by specifying option -c when starting up pro-STAR. Once the desired pro-STAR variant has been chosen. “Commonly used files”. Note that these files contain default (dummy) code to start with and you should edit them as necessary to insert your own code. containing problem data.g. etc. Via STAR-GUIde’s “Run Analysis Interactively” panel. “Subroutine Usage”).BASIC STAR-CD FEATURES Running a STAR-CD Analysis Chapter 2 The precise list of options displayed by the prompt depends on how the pro-STAR environment was originally set up on your particular machine. These are discussed fully in individual chapters of this volume dealing with such topics. However. Step 5 If user-defined subroutines are not required. direct colour or true colour visual that exists for your screen and uses it. File . This way. you may provide input for setting up your model according to the descriptions given in the remaining chapters of this manual.ccm. such as material properties. The most convenient way of doing this is to create both the subdirectory and the files from within the pro-STAR session (see Chapter 14. containing all user-supplied information about the model File . go to Step 6. Type in a response that is appropriate to the workstation or terminal you are using. The STAR-CD solver operates only in SI units and all dimensions must therefore be defined in metres. as shown below: prostar -c This is an 8-bit pseudo colour setting with shared colour map.02 . File . create a subdirectory called ufile and place your subroutine files in it. boundary conditions. From that point on. you are now in a position to run STAR. containing a log (echo) of all instructions issued to pro-STAR during the session • • Depending on the nature of your problem (e. Step 6 Based on the geometrical and physical data of the model just created. it is advisable to check the files created so far in your working directory. as discussed in the section on “pro-STAR Initialisation”. an introductory panel opens up leading you into STAR-CD’s model-building environment.prob. Examples of using this panel are provided in the Tutorials volume. the STAR 2-4 Version 4. The setting causes no screen flashing but requires sufficient available colours to work. whether it requires a special modelling facility such as Lagrangian multi-phase) additional files may be created.mdl. it is possible to scale the mesh dimensions by a scaling factor if non-SI units were used during mesh generation. A detailed description of all commonly used data files is given in Chapter 17. This may be done in one of the following ways: 1. Note that pro-STAR automatically searches for the highest depth pseudo colour.echo. control parameters. Step 4 When you have finished setting up your STAR-CD model. Otherwise. In most cases. and based on the model characteristics specified in pro-STAR. in general. Please note that. however. data distribution and parallel communication libraries) Resource allocation (to choose which machines to use) A full list of such options can be obtained by typing: star -h or star -help The listing will also contain a short description of each option’s purpose. it will be sufficient to type one command. 2. kill or restart a job) Environment (to export environment variables) User coding (to control the compilation and/or linking of user-supplied code) Parallel setup (pertaining to domain decomposition variations. For a single-precision run. A more complete description can be found in Appendix F of this manual.02 2-5 . By exiting from pro-STAR and then running STAR from your session’s shell or command prompt. However. Some cases. STAR automatically recognises the default run-time requirements and proceeds with the CCM analysis without further user input. see “The StarWatch Utility” on page 17-15 for more details. the user can control the operational behaviour of STAR in one of the following areas: • • • • • • Job precision (single or double precision) Job control (to abort. for better bookkeeping. type: star -dp Please note that it is not necessary to provide the case name of the model you are running. one needs to specify the machine (node) resources for running STAR and this input is automatically used to determine the type of run required.Chapter 2 BASIC STAR-CD FEATURES Running a STAR-CD Analysis executable will be run automatically and the analysis results (in terms of solution residuals) will be displayed on a separate window. Briefly. it is still important to keep every case in its own directory. For a large number of cases. The following examples illustrate this point: star star origin star 4 Runs sequentially on the local node Runs sequentially on a host called origin Runs in parallel with 4 processes on the local node Version 4. require the specification of additional options related to both run-time resources and/or behaviour. type: star whereas for a double-precision run. Please refer to Appendix F for a list of such options.drp — droplet data On completion of the run.02 .evn — transient event data case. Step 8 At the start of the analysis.2 Runs in parallel on a cluster of 4 machines with 2 processes each Please note that. The output files generated during the course of the run will be merged and placed in the case’s directory. their syntax and their intended purpose. There is then no visible difference between running in sequential and running in parallel. for parallel cases. STAR will read the following files: • • case.div.vfs — view factors for radiation problems case.ccm — geometry data (plus solution data for restart runs) case. can also be generated. Additional information. one or more problem-dependent files such as • • • case. optionally. which then stops the calculations and writes a file with extension . boundary conditions.ccm) file and thus enables you to inspect the residuals and identify the mesh location(s) where numerical instability has occurred. Divergence is automatically detected by STAR. A number of additional files will also be present in your working directory. such as printout of input data.2 pickle.BASIC STAR-CD FEATURES Running a STAR-CD Analysis Chapter 2 star origin. This occurs when a residual anywhere inside the solution domain reaches a very high value or a numeric overflow condition. etc.prob — problem data and. Extra options exist to cater for special situations which cannot be detected automatically.2 curry. The solution starts to diverge.ccm will contain the current analysis results in a form suitable for post-processing or for starting another STAR run. iteration or time-marching continues until one of the following conditions is met: • • • All the iterations or time steps specified for the current run have been completed. Step 7 Once the run starts. including: 2-6 Version 4. the computational domain decomposition is automatically handled by the star front-end script. The parameters involved in controlling the STAR-CD simulation are set in pro-STAR using the facilities provided by the “Analysis Controls” folder in STAR GUIde. The normalised residual sum drops below a specified value (steady-state runs only). This is identical in format and content to a normal solution data (. Check the condition under which your run has terminated. file case.2 rice. residual histories of the inner iterative loops. as described in Chapter 15.16 Runs in parallel with 16 processes on a host called origin star cheese. “Commonly used files”. The additional information (.rsi — Solution residuals.Chapter 2 BASIC STAR-CD FEATURES Running a STAR-CD Analysis • • • case. the run should be terminated and appropriate adjustments made to the relevant control parameters such as under-relaxation factors. If divergence occurs.run — summary of input data plus numerical statistics and (optional) printout of solution variables case. If the case is subsequently run from initial conditions. information on the global change and monitoring values can be used in the same way as for a steady state analysis. the results of the last run performed are stored in sub-directory RESULTS. Note. The run should therefore be given sufficient time to stabilise before any judgement is made on its progress. Satisfactory completion of steady-state STAR runs can usually be judged by observing the following quantities: • • The residual history printed during the run. It is important that checks are made regularly during the initial stages of the analysis to monitor the solution progress. These are normally translated into warning messages.02 2-7 . that increases in residuals and oscillations in the computed variables during the early stages of a run are not uncommon and should disappear after a few iterations.info) file should also be examined for any signs of numerical problems. Additional files may appear depending on the nature of the problem. The process then repeats itself with the creation of a new RESULTS directory for each new restart. in a form that can be displayed graphically. all current results files (such as the ones listed above) are automatically saved in a local sub-directory called RESULTS. In the latter case.000 and all other RESULTS directories deleted. where xxx stands for the run number. The monitoring values of the dependent variables at a critical location within the solution domain. The above is the minimum number of output files created by a STAR run and you should confirm that they are all present.info — STAR warning messages and (optional) additional numerical statistics case. Neglecting this can result in costly and unproductive runs. or as a backup in case the restart run’s files are corrupted. These should stabilise to the converged solution. In transient calculations. however. Note that. Step 10 Continue with an evaluation of the simulation results (post-processing) using the Version 4.run) file (see Chapter 15 for more information on its contents).xxx. These sub-directories thus contain results obtained at the end of each successive run and are available for future inspection. The sum of the normalised absolute residuals should diminish steadily. Such cases are discussed and explained individually in the relevant chapters of this volume. completion is defined in terms of the elapsed (simulation) time or establishment of a steady state. A description of all commonly used output files appears in Chapter 17. at the beginning of every restart run. Both these files may be inspected via a suitable text editor or via panel “Run History of a Previous Analysis” in STAR-GUIde. Step 9 You should now check the results of the analysis by looking at the run history (. Activating STAR-Launch On Unix/Linux Either double-click the appropriate icon on your desktop (for systems which support this). continue by typing prostar to re-enter pro-STAR. Window layout The key parts of the STAR-Launch main window are highlighted below. mesa [xm] and then supply the case name and other input. no limit on the number of STAR-Launch windows that can be active simultaneously. Using STAR-Launch eliminates the need to enter multiple script names manually. as described in the previous section. as described in Step 3. or else type starlaunch & in an appropriate X-terminal window. glm. There is. several es-tools and the STAR solver. Reply as before to the initial prompt Please enter the required graphics driver Available drivers are: x. If you have previously exited from pro-STAR and run STAR separately (see Step 6 above). Using STAR-Launch STAR-Launch is a graphical interface that provides access to most of the CDadapco modelling tools.02 . STAR-Launch is intended to be used with only one case at a time. however. The 2-8 Version 4. including pro-STAR. xm.BASIC STAR-CD FEATURES Running a STAR-CD Analysis Chapter 2 relevant facilities in STAR-GUIde. and also ensures settings can be saved between sessions and between cases. This will display the STAR-Launch main window shown below: On Windows Double-click the appropriate icon on your desktop. Chapter 2 BASIC STAR-CD FEATURES Running a STAR-CD Analysis Shortcut Buttons provide quick access to the three main functions of STAR-Launch. namely: • • • Setting the working directory Launching a pre-/post-processing tool Running the STAR solver These functions are also accessible through the Main Menubar running along the top of the window. Shortcut Buttons Main Menubar Current Working Directory Workspace for Process Output Run STAR Interactively Launch Pre-Post Tool Set Working Directory Setting the working directory Choose File > Set Working Directory or click the first shortcut button on the main window. The current working directory is displayed to the right of the Shortcut Buttons.02 2-9 . This will display a directory browser as follows: Version 4. This is the directory that will be used when launching a pre-/post-processing tool or running the STAR solver. STAR-Launch will open a new Process Output window as shown below. Starting a pre-/post-processing tool To start a pro-STAR session. If an attempt is made to start another one.02 . which will contain any text generated by the Pre-/Post-processing tool as it starts up. or click the second shortcut button on the main window. select the appropriate entry in the Pre-Post menu. or an equivalent pre-/post-processing tool.BASIC STAR-CD FEATURES Running a STAR-CD Analysis Chapter 2 Navigate to the desired directory and click OK. Only one pre-/post-processing tool can be running at any one time. a prompt will appear asking if the existing tool should 2-10 Version 4. The STAR-Launch window can be resized as necessary to display more of the text appearing in the Process Output window. The tool that will be started from this button is set using the Pre-Post tab of the Preferences dialog. The directory tree will be updated to reflect any valid path entered here. Only tools available in the current installation will be listed in the Pre-Post menu. Note that a path can be entered manually in the Look In entry box at the top of the browser window. The path that will be set on clicking OK is shown along the base of the browser window. more STAR-Launch sessions must be opened. The file is normally written on exit from STAR-Launch and contains details of the last working directory specified by the user. When the STAR solver finishes. .xml file. the ball on the tab of the output window will turn black. the solver is started by clicking Run. accessed from Help > Online Manual. Within this directory. STAR output will appear in a new Process Output window. starProject. When all settings have been made.starlaunch in the users home directory (as given by $HOME).02 . the ball appearing in the Process Output window tab will be shaded red. can be written by STAR-Launch if requested by the user. When a process is active. Choosing Yes will kill the existing process. or clicking the third shortcut button. it will attempt to create a hidden directory. similar to the one shown above for the Pre-/Post-processing tool.Chapter 2 BASIC STAR-CD FEATURES Running a STAR-CD Analysis be closed. detailed information on these options can be found in the STAR-Launch On-line Help. This will change to black when the process is finished. which could result in loss of any unsaved data. It also stores a flag indicating whether this stored path is to be used automatically in a new session. Running STAR interactively Selecting Solver > Run Star Interactively. starProject.xml. The dialog provides several options for running the STAR solver. The various File menu options affecting this are explained below: • File > Open Project — This presents a file browser that should be used to find the required starProject. STAR-Launch will be updated to 2-11 Version 4.xml Another file. This stores settings from the Preferences and Run Star Interactively dialogs. Note that only one STAR solver can be run at any one time from a STAR-Launch session.xml When STAR-Launch is first used. will display the Run Star Interactively dialog shown below. STAR-Launch project files . STAR-Launch will write file launcherGlobal. If multiple solver processes are required.xml.starlaunch directory and launcherGlobal. pro-STAR Initialisation Once the basic GUI mode of operation has been chosen (x. you may choose the desired one by clicking on the file selection icon next to the Case Name box.starlaunch directory. STAR-Launch will read the settings within that file.xml file is also found within the initial working directory.02 . the introductory panel shown below appears. Overtype this by the correct name in the Case Name text box.xml file in the current working directory.starlaunch directory. Note that: (a) If a model already exists in your present working directory. File > Save Project — This will write a starProject. see “Running a STAR-CD Analysis”. If a starProject. (b) If you have more than one model. STAR-Launch start-up procedure When STAR-Launch is first started. will display the Preferences dialog shown below: The options contained here are explained fully in the STAR-Launch Online Help (Help > Online Manual). and use these to configure the initial state of the GUI. one within the initial working directory) will always take precedence over settings obtained from a starProject.xml file. glm or mesa.starlaunch directory. and use these to update the initial state of the GUI. or via the Preferences dialog in STAR-Launch). its name will be picked up automatically by pro-STAR.xml file in the hidden ... If a starProject. Settings contained in a local starProject. STAR-Launch will read all settings within the file. This 2-12 Version 4. Settings within the file will reflect the current state of STAR-Launch.e.BASIC STAR-CD FEATURES pro-STAR Initialisation Chapter 2 • • reflect settings from the new file. it will look for the launcherGlobal.starlaunch directory within the user’s home directory. The desired case name — star is the default name assigned to the current problem at the start of a pro-STAR session.xml file (i.xml file in the hidden .xml file in the hidden . Step 3 above.xml file is also contained in the hidden . Preferences dialog Selecting File > Preferences. File > Save As Default — This will write a starProject. xm. The following three optional inputs may be provided: 1. This will be read to determine the initial working directory. Their state will be saved in the starProject. Input/output window This window. “Commonly used files” for a definition of pro-STAR’s model and echo files. Command Output — displays the time and date of the run. These are described in the sections entitled “Input/output window” below and “Main window” on page 2-15. This is useful when working with facilities that cannot be activated from a GUI panel or dialog box in the present pro-STAR version. 3. Command Input — accepts pro-STAR instructions in the conventional ‘Command keyword plus parameters’ format described in the pro-STAR Commands volume. either as Version 4.mdl 2. Clear this option if the latter applies. This sub-window can be re-sized by dragging the control ‘sash’ (the small square at the top right-hand corner) up and down.Chapter 2 BASIC STAR-CD FEATURES pro-STAR Initialisation activates a File Selection browser (see page 2-33) that enables you to choose the desired model. Click on Continue to display the basic pro-STAR GUI windows or Exit to abort the current session. The Append mode — The session’s user input will be appended to an existing log or echo (. The latter serves as feedback to help determine whether a facility was used properly.echo) file or a new echo file will be created. stored in a file of form case. Refer to the description given in Chapter 17. shown on the next page. All subsequent output in that window are the echo of every instruction issued by the user plus pro-STAR’s response to it. 3. Thus. Command History — provides a numbered ‘command history’ list that keeps track of all pro-STAR instructions issued in the current session. via its corresponding model (. Two windows are displayed automatically immediately following the initialisation stage. it is possible to work in ‘command’ mode at any stage of the model building process despite the fact that the GUI version of the code is active.mdl) file or a brand new case. The Resume mode — This can be either a restart from an existing model definition. in top-to-bottom sequence: 1. plus summary data for the model in hand. consists of the following three sub-windows. Clear this option if the latter applies.02 2-13 . if such data were read in from a Restart file at the initialisation stage. 2. If any of the imported command text needs editing prior to execution. The Command Input sub-window can accept multiple commands by cutting and pasting from the window of another application (e. The Command History sub-window can be re-sized by dragging its control ‘sash’ up and down. “Commonly used files”) or a user macro (see Chapter 16. including those generated indirectly via an external command file (see Chapter 17. Menu choices are translated into their equivalent commands before being added to the list.BASIC STAR-CD FEATURES pro-STAR Initialisation Chapter 2 choices from a menu in the main GUI window (see “Main window” on page 2-15) or as commands typed in the sub-window above. The list can be used in the following two ways: (a) Single-click the command number to copy a command into the Input window and then edit it. Note that: 1.g. (b) Double-click the command number for immediate re-execution. The Command History sub-window will normally list all commands issued to pro-STAR. a text editor). 2-14 Version 4. click the Pause action button under the window (see the above panel) paste in the required group of commands make the necessary changes click the Pause action button again to allow pro-STAR to begin executing the commands one by one 2.02 (a) (b) (c) (d) . Chapter 2 BASIC STAR-CD FEATURES pro-STAR Initialisation “Macros”). such as prompts to supply data. Letting the mouse rest on top of any button causes a brief explanatory legend to appear in a special window provided for this purpose.02 2-15 . Main window The main GUI window. etc. Commonly used functions affecting the model display in the graphics area are also implemented. in the space underneath the graphics area. As a launch pad for those pro-STAR utilities that are available in GUI form. To show messages for the user. cell faces. Such output may become extremely voluminous and may thus obscure the record of primary operations performed by the user. that are directly picked from the main window display with the mouse. splines.g. Clicking the Short Input History button will prevent this and will cause pro-STAR to list only the instructions directly issued by the user. shown below. coordinate values) of items such as vertices. The default display shows: (a) The current plot parameters (see “Plot Characteristics” on page 4-3 of the Version 4. It will also list details (e. in the form of action buttons. The user should click one of the eleven drop-down menus appearing in the menu bar and select one of the displayed choices. These are distributed along the top and left-hand-side borders of the window and are described in Chapter 4 of the Meshing User Guide. is used for the following purposes: • • • For graphical display of various aspects of the current model. Lists Displays lists of all available entities of a certain type (cells. Most of these are covered in Chapter 2 of the Meshing User Guide. as discussed under “Error messages” below.) as well as those currently grouped into a user-defined set. check the output window iii) Red — the command has failed. irrespective of whether it was typed in directly or issued via a GUI operation. (b) A clock display showing the current time and date. Click on the red light to view the error Clicking on the red light displays an Error/Warning Summary pop-up window with more information on what has gone wrong. boundaries. The displayed message is Command: <Command Name> has a Warning. (c) Three status indicators showing the result of processing the latest command. Tools Activates dialog boxes that allow definition and manipulation of basic pro-STAR entities (cells. Another type of tool facilitates routinely-used.BASIC STAR-CD FEATURES pro-STAR Initialisation Chapter 2 Meshing User Guide). 2. The indicators are arranged as a set of ‘traffic’ lights whose significance when lit is as follows: i) Green — the command was executed successfully. “Colour settings” in the Meshing User Guide). vertices. The menu bar The menu bar items are listed below. “File Handling”.02 . the message finally seen on the screen is for the last command that was executed. 4.). File Provides all basic housekeeping utilities. 3. etc. etc. If all goes well. including those related to input/output operations — see Chapter 17. Note that if a GUI operation generates a series of commands. This may be turned on or off by selecting Show Clock or Hide Clock from the Utility menu. a message is issued for each one in turn as soon as it is processed. along with a reference to chapters containing a detailed description of their functionality: 1. Modules Accesses special dialog boxes that set up various STAR-CD model 2-16 Version 4. vertices. splines. The displayed message is Command: <Command Name> has an Error. complex operations such as colour selection and mesh surface lighting effects (see Chapter 4. The displayed message is Command: <Command Name> is Done ii) Amber — the indicator flashes to signal the presence of warning messages in the Output window. Tools > Cell Tool > Edit Types means click Tools in the menu bar. Post Displays the results of a STAR run — see Chapter 1 of the Post-Processing User Guide. 10. menu list items. The relevant panels are listed under this menu. 7. For example. such as the assignment of user-defined functions to keyboard keys. frequently used) panels in the STAR GUIde tree structure (see “Panel navigation system”). Utility Provides miscellaneous utility functions designed to aid model control and development. unless the name is followed by • • an ellipsis (…) which means the item displays a new dialog box. In general. the “>” sign denotes successive mouse clicks on menu names. It also supports special user-controlled operations. such as calculation of cell volumes and distance between vertices — see Chapter 3. 11. Also contains on-line versions of the STAR-CD manuals and tutorials. Favorites (optional) This menu appears only if you have chosen any ‘favourite’ (i. Panels Allows you to set up your own screen buttons or panel tools for performing common pro-STAR operations — see Chapter 16. Version 4. Graph Produces various types of graph — see Chapter 14 of the Post-Processing User Guide. dialog box buttons. Help Displays pro-STAR command help information in a scrolled-text fashion.02 2-17 . then click the Cell Tool item in the drop-down list. “Load-step based solution mode” 5. 8. then click the Edit Types button on the displayed Cell Tool dialog. 9.e. A mouse click on any of the above menu names displays a drop-down list. Throughout this manual. clicking an item on the list starts up the action indicated. “Mesh and Geometry Checking”in the Meshing User Guide. 6. or an arrow (⇒) which means the item opens a secondary list with more items to choose from. Plot Contains most of the facilities and options used for mesh plotting operations — see Chapter 4 of the Meshing User Guide. enabling you to jump to them directly.Chapter 2 BASIC STAR-CD FEATURES pro-STAR Initialisation parameters in connection with (a) Animation control — see Chapter 12 of the Post-Processing User Guide (b) Transient condition definition — see Chapter 5. etc. 02 • 2-18 . Operating mode — command BATCH disables pro-STAR’s periodic prompts to stop or continue displaying long lists of data. It is advisable to use this facility only after consultation with CD-adapco. 4. “Resizing pro-STAR”. as explained in Chapter 16. Default settings are normally used for these but the user can override them at will. If any of these values is inadequate for the model in hand. This may be done by first choosing File > System Command from the menu bar to display the System Command dialog box shown below and then typing system commands in its text box. user-written pro-STAR subroutines by typing command USER. it may be increased by following the procedure described in Chapter 17. Command: SYSTEM This is useful for issuing instructions to the host operating system without having to exit from the pro-STAR environment. They are as follows: 1. Switching from the terminal’s graphics screen to the text screen via command TEXT.BASIC STAR-CD FEATURES General Housekeeping and Session Control Chapter 2 General Housekeeping and Session Control When pro-STAR is initially installed on a computer system. that the code can handle. “Set-up Files” and also in Appendix D. specified mostly via commands typed in the Command Input window. etc. default settings are provided for the program’s fundamental operating features. Screen display control There are several facilities for controlling the screen display during a session. Reporting cpu time required to complete a pro-STAR function by typing command TPRINT. 2. boundaries. can be altered in special circumstances. as follows: • Defining the layout and look of the pro-STAR windows. Communicating with the operating system itself. 3. pro-STAR size — command SIZE lists the maximum number of cells. vertices. 5. The following aspects of the program’s operation are covered: Basic set-up These settings are helpful in establishing an appropriate environment for pro-STAR and for accessing facilities related to the operating system of the host machine. Accessing special. This is applicable only when running a non-GUI version of pro-STAR Version 4. These settings. The desired title and up to two lines of subtitle text should be typed in the text boxes provided. Again. Setting the number of lines that appear on each ‘page’ of the Command Output window during lengthy listings using command PAGE. Providing a descriptive title for the current model that helps to identify each plot produced subsequently — choose File > Model Title from the menu bar to display the dialog box shown below. as in the example shown below: Version 4. Such messages appear in three places: • • • On the standard Output window At the bottom of the main pro-STAR window. Echoing the user input stream to the same device as the output stream (e.02 2-19 . Displaying a history of the most recent commands issued during the session via command HISTORY. Command: Error messages TITLE pro-STAR issues error messages as a result of receiving incorrect commands or if it is unable to execute a valid command for whatever reason. the screen or a disk file) via command ECHOINPUT.g.Chapter 2 BASIC STAR-CD FEATURES General Housekeeping and Session Control • • • • • and is used for controlling terminals that operate entirely either in text or in graphics mode. this applies only when running non-GUI versions of pro-STAR since these do not provide a command history window. after the red indicator light (see page 2-16) On the Error/Warning Summary pop-up panel. rather than displaying a crosshair cursor and reading the user-specified picks off the screen — command CURSORMODE. Reading stored cursor picks from an input file. Note that the above safety features can be switched off using command SAFETY. typed on its own. This is useful if a mistake is made but the user does not notice it until some time later. On the other hand. QUIT. Once all commands up to that point are re-executed. select any item in the list to see the error description at the bottom of the panel. the user should type in a correct command and carry on from there. This might speed up pro-STAR execution but at the potential cost of making any sort of recovery from mistakes nearly impossible. typed as SUCCEED. Command SUCCEED. turning Version 4. tells you (in the output window) whether the previous command produced any errors or warnings. along with a prompt to choose the last command in the list to re-execute. including their error id and command in which the error occurred. Thus. A list of commands issued since the last SAVE or RESUME operation is displayed. it will immediately terminate the pro-STAR session. This can be useful when pro-STAR is run in batch mode. the following operations are useful for error recovery: • Re-executing a named range of previously issued commands by typing command RECALL. The chosen command will normally precede the one where the mistake was made. Error recovery If mistakes are made during a session. Retrieving the state of the model description as it was at the time of the previous SAVE or RESUME operation — command RECOVER. click Clear to close the panel. This can be most conveniently used in conjunction with the HISTORY command above. If you know the cause of the problem.BASIC STAR-CD FEATURES General Housekeeping and Session Control Chapter 2 The panel shows a list of all current errors. where it is not desirable for the job to continue after an error. Otherwise.02 • • 2-20 . reminding you to save the results of the session to a .e. The pro-STAR entities serviced by the buttons are: • • • • • • • C-> — cell sets V-> — vertex sets S-> — spline sets Bk-> — mesh block sets B-> — boundary sets Cp-> — couple sets D-> — droplet sets Each button offers a wide range of possibilities to select. This displays the Quit pro-STAR dialog box shown below. selected using one of the criteria in the secondary drop-down list Unselect — remove some members from the current set. select all entities that are not currently selected and un-select the ones that are New — replace the current set with a new set. by clicking Quit.02 All — select the entire set None — empty out the current set Invert — invert the current set. selection may be done by picking all objects falling within a given geometric range in a local coordinate system. you may deliberately exit from pro-STAR without saving the present session’s work. Each button gives direct access to the following set manipulation options: • • • • • • Version 4. one can collect together all cells or boundaries connected to the current vertex set (and the reverse).mdl file (in case this has not already been done explicitly). Command: QUIT Set Manipulation pro-STAR has extensive facilities for collecting and modifying sets of objects. Selection can also take place by simply using the screen cursor to point to items on the current plot. selected using one 2-21 . i. Alternatively.Chapter 2 BASIC STAR-CD FEATURES Set Manipulation off these features should be used with extreme caution. For example. Session termination The current pro-STAR session is terminated by choosing File > Quit from the menu bar. delete or re-select sets. Using other criteria. These are accessible by clicking one of the coloured buttons down the left-hand side of the main window. formed on the basis of a criterion given in a secondary drop-down list Add — add more members to the current set. Nosave. set) file containing the definition to be deleted. for each of the mesh entities described there. To perform a ‘save set’ operation. Click Delete to delete the set definition. pro-STAR’s built-in file browser may be used to help locate it. Note that it is possible to save and restore useful cell. block. up to 80 characters long Click Write to save the set definition. 2.BASIC STAR-CD FEATURES Set Manipulation Chapter 2 • of the criteria in the secondary drop-down list Subset — select a smaller group of members from those in the current set. The following operations are possible: 1. (b) Select Entry — The location of the set to be deleted. This is done by clicking the INFO button at the left-hand side of the main pro-STAR window.02 . vertex. use the same dialog as above and specify the following information: (a) Set File — The name of the set (. (b) Name — An identifier for the set being saved. spline. To delete a set definition previously stored. select INFO > Recall Set/Surface/View 2-22 Version 4. To perform a ‘restore set’ operation. which selects all cells lying on the surface of the most recent mesh plot and makes them the current set. boundary and couple sets without the need to rebuild them frequently. pro-STAR’s built-in file browser may be used to locate it. 3. as select from the list. If such a file already exists. Further details on the above set selection options are given in Chapter 2 of the Meshing User Guide. C-> offers one extra option. select INFO > Store Set/Surface/View and then click the Sets tab to display the dialog shown below: Commands: SETWRITE SETDELETE The input required is as follows: (a) Set File — The name of the set (. Surface.set) file that will store the set definition. selected using one of the criteria in the secondary drop-down list In addition. 2. etc.02 2-23 . Vertices. cell couples and splines. boundaries. each time Cell plot is chosen from the Plot menu. To perform almost any modelling or post-processing operation on the Version 4. successive plots of the current state of the mesh can be made without needing to build a new set after each new cell definition. Unselect or Subset) Click Recall to recall the selected set. Selecting sets of various entities has two major uses: 1. To display only items in the currently active set. For example. pro-STAR’s built-in file browser may be used to help locate it (b) Select Entry — Select the particular set required by name from the scroll list.Chapter 2 BASIC STAR-CD FEATURES Set Manipulation and then click the Sets tab to display the dialog shown overleaf: Command: SETREAD The input required is as follows: (a) Set File — The name of the set (.) by clicking one of the displayed option buttons (d) Read Option — Specify how the sets to be read in will modify any existing sets by selecting one of the menu options (Newset. pro-STAR plots only cells in the currently active cell set. Note that it is possible to print a summary of all data sets stored so far by typing command FSTAT. SETADD may also be used in the same way for other kinds of sets.e. Thus. i. The status of the selected entry is displayed in the box underneath (c) Choose Data — Specify the type of set to be read in (All. Cells. Add.set) file containing the set definition. Note that command SETADD causes all newly-defined cells to be automatically added to the current set. see Chapter 4. SPLSET and DSET. see Chapter 3. All set operations can also be performed by typing commands CSET. a full list is given under the various boundary type descriptions in Chapter 4.2. “Boundary Region Definition”. plus time for transient cases or iteration for steady-state cases. Basic functionality At present. “Solution Domain Initialisation”. for transient cases. they could be anything of relevance to STAR-CD.02 • 2-24 . For most boundary types. instead of on individual objects or a range of them. or the corresponding on-line Help topics for STAR GUIde’s “Define Boundary Regions” panel. Note that: (a) The applicability of field variable and scalar initialisation tables can be restricted to a selected domain or a cell type (b) The only dependent variable allowed for solid materials is temperature • Source Terms — a description of mass. VSET. (b) When working with commands. in principle. time. These are described in detail in the pro-STAR Commands volume. the independent variables can be the three spatial coordinates. BLKSET. The independent variables may be any combination of spatial coordinates. The only exception is outlet boundaries where only time is allowed (i.5 will modify the X-coordinate of every vertex in the current vertex set. For example: (a) Choosing Lists > Cells from the menu bar and clicking the Show Cset Only option button will list only cells in the current set. momentum or scalar species sources. BSET. for both steady and transient cases.BASIC STAR-CD FEATURES Table Manipulation Chapter 2 currently active set. see Chapter 4. there can be no spatial variation in outflow conditions along the outlet surface).e. For most commonly used tables. heat. CPSET. The dependent variables are normally flow field solution variables but. The permissible dependent variables vary according to the boundary type considered. The permissible dependent variables for fluid materials are listed under topic “Initialisation”. page 4-7. The independent variables may be any Version 4. tables are used principally as a substitute for user subroutines in the following situations: • Boundary Conditions — variable conditions along the surface of a boundary region. page 3-8. Table Manipulation pro-STAR tables are multi-variable entities akin to spreadsheets and can be used to store values for up to 100 dependent variables as functions of a combination of several independent variables. Initial Conditions — non-uniform initial distributions of field variables.VSET. as described in a separate topic for scalar “Initialisation”. the independent variables may be any combination of spatial coordinates and. typing VMOD. Scalar variables representing chemical species mass fractions may also be initialised. 3 0.2 0. Rotational Speeds — variable angular velocity in rotating systems.1 0.3 2-25 .m.0 Version 4. as with initial conditions. The dependent variable is angular velocity.0 20. expressed in r.02 DT 0.1 0.01 0. specified in panel “Rotating Reference Frames”.00 15.3 0.Chapter 2 BASIC STAR-CD FEATURES Table Manipulation • • combination of spatial coordinates and time for transient cases. showing the desired time step variation and the table structure needed to achieve it: 0. the dependent variable the time step size. This is illustrated by the example below. Note that STAR assumes a linear variation in step size between the size values entered at two consecutive time points. Note that. the applicability of source tables can be restricted to a selected domain or a cell type.00 Time (sec) Figure 2-1 Example of time step variation Table 2-1: Time step size table TIME 0. or iteration number for steady-state cases.35 0. specified in panel “Set Run Time Controls”.00 10. The permissible dependent variables vary according to the source type considered.00 5.0 5. a full list is given in the on-line Help topics for the various sources definable via panel “Source Terms”. The independent variable is time.0 5. or iteration number for steady-state cases.0 0.1 0.05 0.2 0.25 DT (sec) 0.0 10.15 0. Run Time Controls — variable time step for transient cases. The independent variable is time for transient cases.p.00 20.0 1. The following two options are available in this category: • Mass Flow Rate — injection rate history. This table may also be specified in panel “Injection Definition”.BASIC STAR-CD FEATURES Table Manipulation Chapter 2 In addition. The same table type may also be used in panel “Injection Definition” as part of an explicit specification of injection characteristics. The basic functionality of the editor is described below.02 . Diameter Distribution Function — a definition of the droplet diameter distribution function. Both options are accessed by clicking the special table editor button at the bottom left-hand side of the main window. a special table type is used to enter problem data for Lagrangian Multi-Phase cases. • The table editor Table data are stored in text files and may be created or modified either via a suitable text editor or via pro-STAR’s own GUI facilities. The table is used in transient analyses only and contains injector mass flow rates vs. click New Table to display the table view shown below: 2-26 Version 4. time (see also topic “Define Injectors”). New tables To create a new table. droplet diameter. in terms of spray percentage mass vs. specified in panel “Spray Injection with Atomization” which activates STAR-CD’s built-in spray modelling facilities. that only the first 30 characters found up to the first space in the string are usable by STAR. Click Setup to confirm your selections and enter the data input mode. Version 4. press and hold down the Shift key. Note. this does not apply to mass flow rate tables. however. by clicking button New in a STAR GUIde panel that requires the use of tables. including spaces. 7. Obviously. as shown in the example below. Select Table Type — choose the basic table type from the list of options described under “Basic functionality”. Out of bound value options — prescribe the action to be taken if needing to calculate dependent variable values at points lying outside the table range. then click the last variable in the group (c) For a random selection. click the first variable. 3. To select an item from this list: (a) For single items. i.02 2-27 .e. the three space coordinates are interpreted as follows: Cartesian x (X) y (Y) z (Z) Cylindrical r (R) θ (ΤΗΕΤΑ) z (Z) Spherical r (R) θ (ΤΗΕΤΑ) φ (PHI) Toroidal r (R) θ (ΤΗΕΤΑ) φ (PHI) The coordinate names shown above inside parentheses should be used as table headers when creating a table outside this GUI environment. click the desired variable (b) For two or more items in sequence. 2. Table Title — enter a title up to 80 characters long. The available options are: (a) Error — issue an error message (b) Extrapolate — use the closest two data points to calculate an extrapolated value (c) Cutoff — use the closest data point as the variable value 4. The correct type is selected automatically if you enter the editor indirectly. Select Independent Variables — all valid variables for the chosen table type are displayed automatically as a series of option buttons. Select Dependent Variables — for boundary and source tables. Depending on your selection. Coordinate System — specify the coordinate system number to be used for spatial independent variables (see “Coordinate Systems” on page 2-8 of the Meshing User Guide). All valid variables for the chosen table type are displayed automatically in the adjacent scroll list. A search button is provided for choosing any of the currently defined systems from the Coordinate Systems dialog. hold down the Cntrl key and then click each variable in turn 6. 5.Chapter 2 BASIC STAR-CD FEATURES Table Manipulation Panel Data Entry To use the dialog facilities directly. Choose those needed to define your table by clicking the corresponding button. the following input is required (reading from left to right along the panel): 1. select also the specific type of boundary or source required from a secondary menu. as in a spreadsheet. The available pairs for the example shown (an X.TIME and the pair chosen is X . by clicking the radio button next to that value in its column on the left-hand side. 2-28 Version 4. a pair of independent variable values are displayed as row and column headings and the user fills in appropriate values for the current dependent variable. The left-hand side of the panel will display a number of columns. (b) Fix the other independent variable(s) to a desired value.Y.BASIC STAR-CD FEATURES Table Manipulation Chapter 2 Commands: TBDEFINE TBCLEAR TBWRITE TBGRAPH The following points should be kept in mind when specifying table data: • Table values should be entered for each dependent variable selected in step 5 above. TIME is fixed to 0. To create such two-dimensional tables: (a) Select the required pair from the Independent Variables menu. Accordingly. Your selection will be automatically reflected in the options shown on Dependent Variables scroll box. Y. Tables containing two or more independent variables are essentially multi-dimensional and need to be specified as a series of two-dimensional x-y tables. one for each independent variable selected in step 6 above. in ascending order. X . noting that pro-STAR activates only those combinations that correspond to the choice made in step 6 above. as shown in the example above.02 • • • . In the example.Y. Fill each column with all the values assumed by that variable in the table. Fill in all required data for the currently selected variable before scrolling to the next one. TIME selection) will be X .TIME and Y . Version 4. pro-STAR’s built-in browser may also be used to locate an existing file. For the purposes of the graph. (b) Go to the graph setup section at the bottom of the panel (which now displays the chosen variable) and select an independent variable from the versus scroll box. you may: 1. This might happen. 2. After opening the Table Editor dialog. Check the table contents graphically by plotting them as a pro-STAR graph (see Chapter 14 of the Post-Processing User Guide). if instead of choosing to enter an X . These values will also appear inside the @ boxes. A simplified display appears in the editor panel in these cases. for example. File Data Entry An alternative method of generating a new table is to import existing tabular data from an ASCII file created outside pro-STAR. (d) Click Graph to see the result of your selection.02 2-29 . you chose instead to enter X .TIME sets for fixed X’s. The file name should have extension .TIME sets for fixed Y’s followed by Y . • Tables for rotational speeds. To use this method: 1. This sets up the 2D table and displays the chosen pair’s values as row and column headings (d) Fill the table with the required dependent variable values and then click Save Data. select the Import button situated under the New Table option. (e) Fix the other independent variable(s) to a different value and repeat steps (b) to (d) above as many times as necessary (f) Select another pair from the Independent Variables menu and fill in another series of 2D tables.tbl and should be entered in the File Name box at the bottom of the panel. This will be plotted along the graph’s y-axis.Y set for a series of fixed TIME’s. these will be fixed to the value indicated by the radio button in each variable’s column.Chapter 2 BASIC STAR-CD FEATURES Table Manipulation (c) Click the FILL button. Once your data input is complete. This will display the alternative panel view shown below. This will be plotted along the graph’s x-axis. (c) The names of the remaining independent variable(s) will also be displayed in the const boxes. run-time controls and Lagrangian multi-phase specifications always have one independent variable and thus involve filling in a two-column table. To use this facility: (a) Select the variable to be checked from the Dependent Variables scroll box. The same also applies to the other tables if only a single independent variable is specified. Click Write Table to save your data in this file. Save your data in a table file. Enter the name of your file in the ASCII Data File Name box.02 .tbl) in the File Name box. 5. Note that: 1. Enter the remaining table specification items on the right-hand side of the panel. Check the table contents graphically. Click Import to import your data into pro-STAR. and then save them in a pro-STAR table file. 7. as described on page 2-27. Check that your own file conforms to this standard and modify if necessary. Existing table display/modification To read and display the contents of an existing table. click Read Table at the top left-hand side of the editor and then enter the file name (of form case. 4.BASIC STAR-CD FEATURES Table Manipulation Chapter 2 2. or use pro-STAR’s built-in file browser to help locate it. as described on page 2-29. You cannot add new dependent or independent variables to an existing table (or delete any that are currently defined) 2-30 Version 4. Click Instruction to open a special text panel giving detailed information on how the user file shoud be structured and formatted. its contents can be checked visually using the graph function described in the previous section or modified as required. pro-STAR’s built-in browser may be used to help locate the file. 3. if required. Select option space or comma from the Delimiter menu to indicate how the numerical values in your table are separated from each other. Commands: TBREAD TBLIST TBMODIFY TBGRAPH Once the table has been read. 6. You may use command TBSCAN to scan a named . At the end of the editing session. Only one table at a time may be loaded into the pro-STAR editor. The user specifies which tables will be needed as part of the boundary. Changes to existing dependent variable entries are made by over-typing and confirmed by clicking Save Data. This setting may also be accessed from the menu bar by switching between options Plot > Standard Plot Mode and Plot > Alternate Plot Mode. The scale factor applied when saving model geometry data (see Chapter 17.prob)”) so that they are available to STAR during the run. Click Save Modified Data to confirm the changes. Apart from the table file itself. Note.02 2-31 . TERMINAL. you must first save the current one to a named file (if you have made changes) before reading in the new one. • • The basic features of devices operating under one of the above modes are: 1. clicking New Table enables you to erase all entries and start afresh. 3. Information about its contents is displayed in the I/O window. If you change your mind about the contents of your current table and wish to make drastic change. but are not generally capable of filling in closed polygons or erasing parts of the plot after drawing in them. The plot destination — this specifies whether plots are to appear directly on the screen or written to the neutral plot file (see Appendix B in the Post-Processing User Guide).ccm)”) is also applied to table coordinate data when they are accessed by STAR. 4. table data needed for the next STAR-CD analysis are also stored in the STAR problem file (see Chapter 17. Plotting Functions Basic set-up The basic hardware-related plotting features are set by a single command. you should always save your updated table in a named file by clicking Write Table Useful points 1. The operating mode of the plotting device — a choice between raster. can draw lines in one or more colours. initial condition or other model specification requiring the use of tables. 2. 5. You may alter both individual values and the number of such values for any independent variable. “Problem data file (.Chapter 2 BASIC STAR-CD FEATURES Plotting Functions 2. This command sets: • The display mode of X-based terminals (use option ALTERNATE only for improving the plotting speed of certain older types of workstation). If you need to access a second table. however. that this option is available only if you are working with the glm version of pro-STAR (see “Running a STAR-CD Analysis”. Step 3). 3. It is also possible to toggle between raster and extended plot mode by clicking the X / GL button at the bottom left-hand side of the main window.tbl file. “Data repository file (. such as pen plotters. When this mode is set: Version 4. 4. vector or extended (for high-performance workstations). Vector devices. 3. (c) Added lighting effects to enhance a user’s perception of the model geometry. etc. Restoration of the original screen settings — command RESET. (b) Contour plots are rendered in filled colours. On-line retrieval of screen images previously stored with SCROUT — command SCRIN. Postscript laser printers.02 • • • • 2-32 . The window is also enlarged to take up almost the entire screen. hardware Z-buffers. etc. translation and zooming of plots. Advanced screen control Advanced screen control functions are implemented as follows: • Background/foreground colour reversal — from the menu bar. Maximising the graphics area — from the menu bar. Gouraud shading. use command WHOLE. Machines with these high-specification graphics attributes can provide: (a) Real-time rotation. the user wants fringe-style rather than filled-colour contour plots.BASIC STAR-CD FEATURES Plotting Functions Chapter 2 (a) All hidden-line plot calculations are done by software. are capable of filling in polygons quickly and overwriting previously coloured-in regions with new colours. on-line storage of complete screen images — command SCROUT. (b) Contour plots rendered in smoothly varying colour bands. When this mode is set: (a) Hidden-line plots are done by hardware. Appendix C in the Post-Processing User Guide lists all currently available combinations of plot mode and plot characteristics. for example. This command also provides an elementary animation facility. double-frame buffering. such as most workstation screens. use command CLRMODE. 2. select Plot > Background > Standard (for white lines and text on a black background) or Plot > Background > Reverse (for black lines and text on a white background). This is helpful when making animations since the largest number of pixels are used. (c) All contour plots displayed as line contours rather than filled colours. Select Plot > Standard Plot Screen to return the window to its default size and appearance. Alternatively. Version 4. (b) Large amounts of time may be required for large models. by replaying a sequence of screen images in quick succession. thereby obtaining the highest possible plotting resolution. Alternatively. (c) VECTOR mode operation is still possible if. This style of plot is limited to machines that support the OPENGL standard and cannot be stored in the neutral plot file at present. Extended mode devices offer additional functionality such as true (24-bit) colour. coordinate transformation pipelines. The same information can also be listed on line by choosing Help > pro-STAR Help from the menu bar and then selecting the COMBINAT item from the list shown at the bottom of the pro-STAR Help dialog. Raster devices. select Plot > Maximum Plot Screen to hide the GUI buttons surrounding the graphics area so as to make the plot as large as possible. Temporary. either Level 1 or Level 2 format) EPSF (Encapsulated PostScript. pro-STAR provides this facility via the Utility > Capture Screen menu option (or by typing command SCDUMP). in the Utility menu (alternatively. Image display control — command PLTBACK. The result of this operation is the creation of a new window containing the picture currently displayed in pro-STAR’s main graphics area. Customised scaling of text fonts used in pro-STAR — command TSCALE. High Res. Selecting any of the above options opens the File Selection dialog shown below. either Level 1 or Level 2 format) The user needs to make sure that the choice of format is appropriate to the end application. Screen Dump.Chapter 2 BASIC STAR-CD FEATURES Plotting Functions • • • Deletion of screen images previously stored with SCROUT — command SCRDELETE. The latter can then be pasted into a document created by another. say presentation or word-processing. This enables images to be created and stored in memory and then popped onto the screen (as opposed to displaying them as they are being created). The picture can be subsequently saved in a file by choosing Utility > Save Screen As and selecting one of the following options for the file format: • • • • XWD (X Window Dump) — X-Motif version of pro-STAR only GIF (Graphics Interchange Format) PS (PostScript. use command HRSDUMP). application. This appears as an additional option. you also have a choice of saving a high-resolution screen dump (HRSD) of the extended mode plotting window. If you are working in OpenGL extended graphics mode (see page 2-32). refer to the pro-STAR Commands volume.02 2-33 . Selecting this Version 4. For further details on using the above commands. enabling you to specify the name and destination directory of the picture file. Screen capture It is often very useful to be able to save the contents of the graphics screen as a picture file. It is also possible to use the HRSD facility in batch mode to produce high-quality plots using OpenGL style graphics (i. special lighting effects.e. etc. 3. Clicking the Options button opens a secondary Image Options dialog that enables you to specify the required image resolution and/or page properties (for PostScript files). Enter the file name in the box provided.exte 2-34 Version 4. You do not require a special OpenGL graphics card on your machine to do this. the pictures can be made off-screen using the ‘mesa’ software emulation of OpenGL as follows: • Run pro-STAR with mesa graphics in batch mode prostar mesa -b • Set extended mode graphics term.BASIC STAR-CD FEATURES Plotting Functions Chapter 2 option from the main menu opens the High Resolution Screen Dump dialog shown below: The user input is as follows: 1. Clicking the adjacent browser button opens the File Selection dialog shown above which helps locate the required file.. including translucency. Select the required file format from the File Type menu as one of (a) (b) (c) (d) png gif ps (PostScript) eps (Encapsulated PostScript) 2.02 . An example for GIF/PNG images is shown below.). resolution. Select Item and pro-STAR Help. you need solid knowledge of Tcl/Tk programming. About pro-STAR. shown below.tcl assign the path to this file to an environment variable called STAR_TCL_SCRIPT Getting On-line Help The Help menu in the main pro-STAR window is divided into three parts. with widget callbacks designed to pass pro-STAR command strings back to pro-STAR (much as it happens now when you click a button in STAR GUIde). etc.) The Users Tool The Users Tool enables you to create your own customised user interface.ps file) You can also use the various options to change image size.Chapter 2 BASIC STAR-CD FEATURES The Users Tool • Set up the model as you wish.png (write a . resolution. by running a Tcl/Tk script from within pro-STAR by means of a built-in interpreter. as shown below: Version 4. To make use of this tool. just as for interactive mode above (see the HRSD command Help on options for setting image size. and then use the HRSD command as follows: hrsd. Clicking the left-hand button invokes the built-in interpreter which then runs your script. etc. There are three options in the top part.02 2-35 .test. it is important to • • save your Tcl script in a file called STARTkGUI.output.png file) hrsd. An introductory panel.png..ps. To use this facility. by choosing Tools > Users Tool.ps (write a . Clicking About pro-STAR displays pro-STAR version information. including any CPLOT/REPLOT operations needed to display the picture. The basic idea is that the user builds a dialog box as he/she would for any other Tcl/Tk-based application. is provided via the main menu. grouped by command module and listed in alphabetical order A list of all database files available under pro-STAR pro-STAR environment variable definitions All file extensions used A description of pro-STAR’s macro files A description of pro-STAR’s user-defined Motif panels A tabulation of radiation parameters required for walls and baffles Units for all physical quantities used in STAR-CD A list of user subroutine names and brief descriptions A list of all GUI tools and dialog boxes Help on any of the above items is obtained simply by selecting the appropriate title in the scroll list underneath the main information display area. In addition. the default listing of any user subroutine may be displayed by selecting item UserSubs from the Module pop-up menu and then choosing the 2-36 Version 4.02 .BASIC STAR-CD FEATURES Getting On-line Help Chapter 2 Clicking pro-STAR displays the pro-STAR Help dialog shown below: This dialog contains on-line information on: • • • • • • • • • • • • Conventions regarding command line syntax All valid combinations of plot mode and plot characteristics One-line summaries of every pro-STAR command. consisting of Release Notes for the current version. Methodology. The last section of the Help menu activates your machine’s web browser and directs it to useful web sites set up by CD-adapco. Tutorials and also the CCM. Version 4. • • An example of command help is shown below: The middle section of the Help menu gives on-line access to every volume in the STAR-CD documentation set. users must make sure that Adobe’s Acrobat™ Reader is installed on their machine. by choosing option Select Item from the Help menu. Details on the functionality and syntax of every command may be displayed as follows: • • By typing the command name in the Find Command text box and pressing Return By selecting the appropriate command module from the Module pop-up menu (see the pro-STAR Commands volume for a description of modules) and then choosing the required command name in the scroll list By searching through the available help text for a keyword. pro-STAR Commands. Such an action will automatically display the corresponding command description for that part of the window.02 2-37 . There is also a Help section containing useful information on how to best use Acrobat for viewing on-line help text corresponding to each panel of the STAR GUIde system described below. as typed in the Keyword text box In a context-sensitive manner. This changes the mouse pointer from an arrow to a ‘hand’ (Help) pointer with which you can click any part of the main pro-STAR window. To view these documents. Meshing and Post-Processing User Guides. Instructions on how to do this are given in the STAR-CD Installation and Systems Guide.Chapter 2 BASIC STAR-CD FEATURES Getting On-line Help required subroutine name from the second scroll list. 02 . This displays the introductory screen shown below. displaying pre-defined groups of panels relating to each of the activities so that the user can specify model parameters and characteristics pertinent to the current activity. a tool for guiding the user through the various stages of the model building process. the STAR GUIde panels cover a subset of pro-STAR’s capabilities. On the right is the initial Help screen explaining how STAR GUIde works and what its function buttons do. guiding the user through the modelling process in a logical sequence so that no steps of that process are overlooked. Selecting Tools > STAR GUIde from the menu bar 2. This is replaced by the contents of the current process panel as you go through each stage of model building. STAR GUIde may be accessed from pro-STAR’s main window using either of the following two methods: 1.e. Clicking the STAR GUIde button at the top left-hand side of the window. The panels and their groups are shown as a tree structure within the NavCenter sub-window. • At present. These stages are represented by panels and are subdivided into logical groups. Additional capabilities are being continually added and appear in each new version of STAR-CD. It works by • • dividing the CCM analysis task into groups of major modelling activities. i. The screen consists of two parts: • On the left is the Navigation Centre (NavCenter). • 2-38 Version 4.BASIC STAR-CD FEATURES The STAR GUIde Environment Chapter 2 The STAR GUIde Environment STAR GUIde represents the latest development in easy-to-use GUI tools for building STAR-CD models. those that relate to the most common tasks of the modelling process. 3. Click on one of the yellow folder icons (or on the text next to them) to open and close the folder and to display its constituent process panels and sub-folders. Each process panel enables you to enter or generate data needed to complete that process. the input for a given process is distributed amongst colour-coded. Click on a grey panel icon (or on the text next to it) to open the panel.Chapter 2 BASIC STAR-CD FEATURES The STAR GUIde Environment The following points should be borne in mind when using this tool: 1.02 2-39 . ‘file tabs’. These are brought to the forefront by clicking on the appropriate tab. The NavCenter tree contains a set of yellow folder icons representing each major modelling activity and acts as the starting point for defining your own model. 2. its contents will be displayed on the right-hand side of the STAR GUIde window. 4. Where appropriate. The colour coding depends on the entity (block. A complete STAR-CD simulation can be set up and run by performing the activities in the folder tree and in the order shown. etc. cell.) being processed and is consistent with the colour coding used in the main Version 4. spline. The reverse operation is performed by choosing Remove from favorites. including descriptions of the data required. clicking Favorite and then choosing the Add to favorites option. 6. free-floating dialog box. A ‘favourite’ panel is selected by first displaying it in STAR GUIde. explanations of the choices available. Help screens use Adobe’s Acrobat™ Reader system. This happens whenever such a dialog provides the most convenient means of entering the data required.02 . without first opening the STAR GUIde window and then searching through the NavCenter tree. click the Close STAR GUIde button at the bottom of the NavCenter sub-window. Information on how to best use Acrobat for reading these screens is given under the Help menu in the main pro-STAR window (option Help). The window may be expanded back to its original size by clicking this button again. 5. Help — provides concise information on the current panel.BASIC STAR-CD FEATURES The STAR GUIde Environment Chapter 2 pro-STAR window. their contents therefore appear in a separate window opened by that system. 2-40 Version 4. The function of each button is as follows: Go Back — returns to the previously selected panel. suggestions on things to look out for. Panel navigation system The set of five buttons at the top right-hand side of the STAR GUIde window are designed to help you navigate through the system and get more information about what to do. i. The current favourites are listed under the Favorites menu in the main pro-STAR window. Collapse/Expand Navcenter — Closes the left-hand (NavCenter) side of the STAR GUIde window to make more space on your screen. etc. To exit from the STAR GUIde.e. In some instances. clicking a button on a panel activates a separate. Favorite — enables you to store the names of frequently used panels so that you may jump to them directly. Version 4. including those described in the Tutorials volume: 1. goes forward to the most recently displayed panel. if necessary. the structure and meaning of individual commands. all three windows should be displayed side-by-side on your screen. as shown below: General Guidelines The following general guidelines should be kept in mind when running STAR-CD models. Take advantage of the on-line Help facilities to check the code’s conventions and. The input/output window should also be displayed to cater for operations that need command input (see also the “Introduction” section). command_name in the pro-STAR I/O window. STAR GUIde usage The STAR GUIde panels should be used in conjunction with the facilities (pop-up menus and action buttons) offered by the main pro-STAR window.Chapter 2 BASIC STAR-CD FEATURES General Guidelines Go Fwd — if the Go Back control has already been used. These facilities are accessed either from the GUI Help menu (see “Getting On-line Help”) or by typing HELP. For maximum ease of use.02 2-41 . PROPERTY.BASIC STAR-CD FEATURES General Guidelines Chapter 2 2.mdl file. system crashes. or if you want to check the commands that were generated automatically by a particular GUI operation. 3. so make sure you are in the right module by typing the appropriate keyword (MESH. and continue from there 5. Display the relevant STAR GUIde panels frequently to check the settings of pro-STAR parameters. split lengthy model-building sessions into several parts. re-execute the code up to the one that went wrong. This safeguards against unexpected mishaps (power failures. 4. To continue working on the model. 6. Mistakes in pro-STAR can be rectified in two ways: (a) Use option File > Resume Model (or command RESUME) to go back to the state of the model saved with the last SAVE operation and start again from there (b) Use command RECOVER to play back all commands issued since the last SAVE operation. the screen information relates to the active command module. re-enter pro-STAR as discussed in Step 10 on page 2-7 and then perform the next operation. make sure that the model is in a satisfactory state before saving it. in some machines it will abort the entire pro-STAR session. Note that command execution can be terminated half way through in the following circumstances: (a) By typing Abort instead of a parameter value while supplying parameter values to a command in ‘novice’ mode. However. Remember that all pro-STAR windows can be re-sized using the mouse. etc. This is particularly helpful when you need to use commands for a particular operation. Make frequent use of the File > Save Model option (or command SAVE) to store the current state of your model description on the pro-STAR model file (. In the latter case. Note that the effect of this operation is machine-dependent and therefore great caution should be exercised in its use. etc. however. by using option File > Quit (or command QUIT) at any convenient point in your current session and then saving your work on the . You should. alternatively use command STATUS. 2-42 Version 4.trns) file has to be explicitly re-connected to the pro-STAR session by using the Connect button in the Advanced Transients dialog (or command TRFILE).) 7.) by enabling you to restart your work from the point where the last SAVE operation was performed. remember that for transient problems the transient data (. (b) By typing Ctrl+C while waiting for a command to finish processing. If necessary. CONTROL.02 .mdl). It is recommended that both the I/O and the main window are positioned and sized so that both are visible simultaneously. Introduction The Cell Table The process of setting up properties is usually quite simple and relies on the concept of cell identity and the consequent use of the cell table. porous materials. Version 4. as shown in the dialog below. where there is no mixing of fluid streams. as discussed under “Cell types” on page 2-37 of the Meshing User Guide. This enables the user to specify a • • • • • • • • • • • • • cell table index cell type material number colour table index porosity index spin index group number surface lighting material index processor number conduction thickness radiation switch initial free-surface identifier identifying name for a set of cells. The meaning of the various parameters that may be set in this table is described in “Cell properties” on page 2-38 of the Meshing User Guide.02 3-1 .Chapter 3 MATERIAL PROPERTY AND PROBLEM CHARACTERISATION Introduction Chapter 3 MATERIAL PROPERTY AND PROBLEM CHARACTERISATION The physical properties of the fluid and/or solid materials within the model are typically defined immediately after setting up the mesh and performing a thorough visual and numerical check on it. solids materials. All cells in the mesh can be indexed and differentiated in various ways with the aid of an entry in the cell table. STAR-CD can analyse problems containing arbitrary combinations of • • • multi-domain fluids. accessed by clicking the CTAB button on the left-hand side of the main pro-STAR window. The cell table can be defined using pro-STAR’s Cell Table Editor. Different materials are identified by separate material property numbers. This is done by typing different values in the Color Table Index or Lighting Material text boxes. 1). Baffle. Another possibility is to index cells on the basis of a common group number.). a distinct portion of the mesh. typed in the Group Number text box.g.02 • • • • • • • • 3-2 . Solid. in the diffuser model shown in Figure 3-1 there is a single material number (no. A new entry is set up by clicking on the next available number in the list and then specifying the relevant cell properties. respectively. etc. material number 1 refers to air properties at standard conditions.MATERIAL PROPERTY AND PROBLEM CHARACTERISATION The Cell Table Chapter 3 Commands: CTABLE CTDELETE CTNAME CTCOMPRESS CTMODIFY CTLIST The rules governing the use of the cell table are as follows: • All entries in the table are identified by an index. e. selected from the editor’s pop-up menu. All cells linked via a common index belong to a common Cell Type (Fluid. Cell indexing normally differentiates the cells’ material type. However. Colour selection is facilitated by clicking the multi-coloured button next to the Color Table Index box. The corresponding colour number is then automatically entered into the box. By default. This opens a Color Palette panel where the desired colour is selected by simply clicking the appropriate square. Thus. typed in the Material Number text box. Such objects might typically be generated with the help of an external CAD package and Version 4. but the cells can be indexed to different colours or different types of surface shading (see Chapter 4 of the Meshing User Guide). listed under the Table # heading in the editor’s scroll list. This groups together all cells belonging to a particular ‘object’. corresponding to the one and only domain in the model. it can also be used purely for visual and/or selection purposes. The default cell table index is number 1 and is associated with a fluid whose material number is 1. Every cell in the model is associated with a cell table index. 2. Cell index 1 Colour 2 Cell index 2 Cell index 3 Colour 3 Colour 4 Figure 3-1 Cell indexing to implement differentiation by cell colour Cell table entries may be displayed at any stage of the pro-STAR session by clicking CTAB on the main window. Note that all cells indexed to this entry must be deleted or changed to a different index before the table entry itself can be deleted. index. This can be done by: (a) Pointing at the desired cells with the screen cursor — choose option Modify Type > Cursor Select. The active cell type can be changed at any time by highlighting the type required in the Cell Table list displayed by the Cell Tool and then clicking the Set Active Type button. by taking on the index that is active at the moment of their creation. Group numbers are normally generated automatically as part of the data import function (see “Importing Data from other Systems” on page 3-1 of the Meshing User Guide). Cell table entries can be further identified by a name. (b) Changing all cells contained within a polygon drawn on the screen with the screen cursor — choose option Modify Type > Zone. by collecting together a group of cells and then changing their identity to the currently-active type. The action is terminated by clicking on i) the same point twice to complete the polygon. Version 4. typed in the Name box. The action is terminated by clicking the Done button displayed on the plot.02 3-3 . Any identifier. or reference number used in a cell table entry may be changed to a different value simply by selecting the entry in the Cell Table Editor’s scroll list and making the required changes. The selection is indicated in the list by a letter ‘A’ against the active type.Chapter 3 MATERIAL PROPERTY AND PROBLEM CHARACTERISATION The Cell Table • imported into pro-STAR using IGES or VDA data files. A cell table definition is confirmed by clicking the Apply button. This removes all redundant entries and re-numbers the remaining ones. This may be done in two ways: 1. Tables that contain deleted (or undefined) entries such as this may be cleaned up by clicking the Compress button. Implicitly. Cell table entries may also be deleted by clicking the Delete button. Explicitly. Cell indexing Cells are assigned an identity (cell index) using the Cell Tool shown overleaf. click Change Type. (c) Changing all surface cells encountered when searching from a starting position given by a ‘seed’ vertex (see the description on page 2-49 of the Meshing User Guide). The cell or cell range to be changed must first be selected on the list. This can be done by choosing option Modify Type > Surface (New Edge Vertex Set) (or Surface (Current Vertex Set)). The ‘seed’ vertex is selected with the screen cursor. Commands: CTYPE CCROSS CFIND CZONE CTCOMPRESS Another method of making changes is via the Cell List dialog. 3-4 Version 4. This may be displayed by clicking the Cell List button on the Cell Tool or choosing Lists > Cells from the main menu bar.02 .MATERIAL PROPERTY AND PROBLEM CHARACTERISATION The Cell Table Chapter 3 ii) the Close button displayed. (d) Changing all cells in the current cell set — choose option Modify Type > Cell Set. to abort the selection operation. shown overleaf. To change the associated cell type. choose a different cell table index on the displayed Change Cell Table box and then click Apply. iii) the Abort button displayed. to let pro-STAR complete the polygon. involving multiple fluid domains in the presence of solids. option Double Cells (see “Microscopic checking” on page 3-28 of the Meshing User Guide).Chapter 3 MATERIAL PROPERTY AND PROBLEM CHARACTERISATION Multi-Domain Property Setting Command: CMODIFY The result of the above process can be checked using the Check Tool. The most general case. This will verify whether a cell table entry exists for every cell within the range specified. is illustrated in the example below: Domain 1 Metal plate Domain 2 Figure 3-2 Version 4.02 Multi-domain flow with solid material domains 3-5 . Multi-Domain Property Setting The user is free to define as many material types (of the fluid or solid variety) as are necessary to represent the problem conditions. The appropriate settings to be supplied via the Cell Table Editor for the example shown in Figure 3-2 are as follows: Domain 1 Metal plate 3-6 Version 4.MATERIAL PROPERTY AND PROBLEM CHARACTERISATION Multi-Domain Property Setting Chapter 3 Setting up models Step 1 Create an appropriate set of cell types and material indices for your model during mesh generation.02 . using the procedure described in “The Cell Table” on page 3-1. • Each domain must be selected in turn via the Material # control at the bottom of the panel (see also the “Liquids and Gases” Help topic).Chapter 3 MATERIAL PROPERTY AND PROBLEM CHARACTERISATION Multi-Domain Property Setting Domain 2 The Material Number indices 11. Note that different cell table indices 1. even if domains have identical physical property sets. solar radiation or solid-fluid heat transfer) prevailing in your model by making the relevant selection(s) in the “Thermal Options” panel. Special considerations regarding the analysis of compressible flows are discussed in “Compressible Flow” on page 3-9 of this chapter. 12 and 13 above refer to the physical property sets associated with each fluid domain and with the solid plate domain. In cases with multiple domains it is recommended that each domain is given a separate material number. Step 3 Set the physical properties of each fluid domain by opening sub-folder Liquids and Gases and then entering numerical values and/or selecting appropriate options in the “Molecular Properties” panel. Non-Newtonian flow may be simulated by selecting the relevant molecular viscosity calculation option. Version 4. Step 2 Open the Thermophysical Models and Properties folder in STAR GUIde. For thermal problems. specify any special thermal transfer conditions (radiation. 2 and 4 are also assigned to each of these because each cell table index can only refer to one material number. This is to allow each domain to have its own initialisation. Note that: • The option chosen for density calculations determines whether the flow is treated as compressible or incompressible. reference values and residual normalisation. The treatment of non-Newtonian fluids is discussed further in “Non-Newtonian Flow” on page 3-11 of this chapter.02 3-7 . Special considerations regarding the use of this option are discussed in “Heat Transfer In Solid-Fluid Systems” on page 3-16 of this chapter. choose an appropriate option from the “Turbulence Models” panel. turbulence or enthalpy equation.02 • 3-8 . The enthalpy equation solver for solid materials is activated simply by selecting Solid-Fluid Heat Transfer in the “Thermal Options” panel. If your model contains multiple solid domains possessing different properties. fluid injection or withdrawal. Step 9 For buoyancy-driven or any other problems involving body forces. Step 5 For turbulent fluid domains. Step 6 For thermal problems. Step 10 If necessary. The reference temperature and monitoring cell location for solids is specified via a separate “Monitoring and Reference Data” panel under the Solids folder. a fan driving the flow at some location of your model. where the fan is not explicitly modelled (tab Version 4.g. turn on the enthalpy equation solver in all fluid domains using the “Thermal Models” panel. specify the necessary parameters using the “Buoyancy” panel. The type of source is chosen by selecting the appropriate tab in STAR GUIde’s “Source Terms” panel (sub-folder Sources): • Mass — specify mass sources or sinks. specify mass sources or additional source terms for the solution of the momentum. Special considerations regarding the use of subroutine FLUINJ for this purpose are discussed in “Fluid Injection” on page 3-21 of this chapter. Solids. Step 8 Set the reference quantities (pressure and temperature) and monitoring cell location(s) for each domain using the “Monitoring and Reference Data” panel (Liquids and Gases folder). Momentum — specify momentum sources.MATERIAL PROPERTY AND PROBLEM CHARACTERISATION Multi-Domain Property Setting Chapter 3 Step 4 If you have selected the solid-fluid heat transfer option. to be used in the solution of the mass conservation equation (tab “Mass”). an additional sub-folder.e. Special considerations regarding the use of this option are discussed in “Buoyancy-driven Flows and Natural Convection” on page 3-20 of this chapter. i. e. Step 7 Specify initial values for the flow variables in each fluid domain using the “Initialisation” panel (Liquids and Gases folder). Specify the physical properties of the solid material by entering numerical values and/or choosing appropriate options in the “Material Properties” panel. will appear in the STAR GUIde tree structure. Further details are given in “Turbulence Modelling” on page 3-12 of this chapter. each domain may be selected in turn via the Material # control at the bottom of the panel (see also the “Solids” Help topic). The temperature distribution inside solid materials is specified via a separate “Initialisation” panel under the Solids folder. Step 3 Set up boundary conditions that are appropriate to the type of flow being analysed. Step 2 Declare the flow as (ideal gas) compressible by selecting option Ideal-f(T. Also included are cross-references to appropriate parts of the STAR GUIde on-line Help system. In sub-folders Liquids and Gases and Solids. Compressible Flow The theory behind compressible flow problems and the manner of implementing it in STAR-CD is given in the Methodology volume (Chapter 16. Turbulence — specify sources appropriate to the turbulence model used.g.P) from the “Density” pop-up menu. All property and physical model settings in your problem may be inspected by selecting the relevant panels in the Thermophysical Models and Properties folder. 1 below) Wave transmissive (for transient flow) Supersonic flow (Ma > 1 throughout the solution domain) Inflow Inlet Inlet Version 4. Enthalpy — specify heat sources or sinks. but see point no.02 Outflow Outlet Pressure 3-9 .Chapter 3 MATERIAL PROPERTY AND PROBLEM CHARACTERISATION Compressible Flow • • “Momentum”). This effectively switches on the compressibility calculations by making the density a function of both pressure and temperature. These may be additional source terms or. in the case of the k-ε model. open each constituent panel in turn and scroll through the available materials. This section contains an outline of the process to be followed when setting up such problems and important points to bear in mind. “Compressible Flows”). radioactive sources in a nuclear reactor cooling problem (tab “Enthalpy”). Alternatively. type command MLIST to display a brief or comprehensive listing of properties for any material in the Output window. These are as follows: Subsonic flow (Ma < 1 throughout the solution domain) Inflow Stagnation conditions Inlet Inlet Inlet Outflow Pressure Pressure Outlet (for steady flow. replacements for the existing terms (tab “Turbulence”). e. Setting up compressible flow models Step 1 Go to panel “Molecular Properties” in STAR-GUIde and select each compressible fluid domain via the slider at the bottom of the panel. containing details of the user input required. However. For inviscid flows.g. In such a case. Useful points on compressible flow 1. ε if appropriate) is based on the momentum (and k. the inlet boundary surface). a ‘well posed’ problem. The combination of inlet and outlet boundary conditions for subsonic flows presented under Step 3 above does not constitute. mass and enthalpy and terminate the solution process after a sufficiently large number of iterations.g. say. If pro-STAR’s automatic meshing module is employed for this purpose. If the mesh is imported from a package that lacks these facilities. it is possible to calculate temperature from a constant 3-10 Version 4. users should designate the known pressure as the reference pressure and make sure the corresponding cell location lies as close as possible to the known location (e. 3. 4. If such meshes contain supersonic inlet boundaries then. to obtain a stable/convergent solution. residual normalisation for momentum (and k.MATERIAL PROPERTY AND PROBLEM CHARACTERISATION Compressible Flow Chapter 3 Transonic flow (Ma < 1 and Ma > 1 within the solution domain) Subsonic Inflow Stagnation conditions Inlet Supersonic Inflow Inlet Supersonic Inflow Inlet Subsonic Inflow Stagnation conditions Subsonic Outflow Pressure Pressure Subsonic Outflow Pressure Supersonic Outflow Pressure Supersonic Outflow Pressure The user should refer to the on-line Help text for panel “Define Boundary Regions” (especially that for “Inlet” boundaries) for a description of how to set up boundary conditions for this type of flow. ε) flux values at the inlet. However. The success of the simulation will depend on the magnitude of the Mach number.g. In this situation. strictly speaking. Special considerations apply to tetrahedral meshes or meshes containing trimmed (polyhedral) cells. you must extrude the mesh in a direction normal to the boundary and then shift the boundary location to the edge of the newly-created. Ma > 0. this is based on the magnitude of the normalised residuals). In the case of a transonic problem with subsonic inflow. this may place an unnecessarily stringent condition on the built-in solution convergence criterion (as discussed in Chapter 1.001 for pressure) in order to obtain a converged solution.7) very low under-relaxation factors will have to be specified (e. because of the large difference in velocity magnitude between the inlet and the rest of the flow field. 2. it is offered as an option for use in circumstances where the pressure is known at the inflow (or at some other point inside the solution domain) but not at the outflow. use its built-in mesh generation capabilities. as usual. it is necessary to create at least two cell layers immediately next to the boundary (see Figure 4-5 on page 4-23). it could be more appropriate to inspect the convergence history of. For the higher Mach numbers (e. “Monitoring the calculations”.02 . layered structure. 0. 2. This section contains an outline of the process to be followed when specifying non-Newtonian fluids and includes cross-references to appropriate parts of the STAR GUIde on-line Help system. text boxes EM and EN) or call subroutine VISMOL (option User). Useful points on non-Newtonian flow 1. In the case of flow through ducts of non-uniform cross-section where supersonic conditions are expected over the whole or part of the solution domain. 6. To do this. If any of these effects are significant. It could be advantageous. The model parameters are functions of temperature. “Non-Newtonian Flows”). Bear in mind that constitutive relations for non-Newtonian flow are basically empirical curve-fitting formulae. it is sometimes necessary to under-relax the initial velocities. It is therefore inadvisable to use them beyond the range of the available data. To do this. This is done by activating special flux under-relaxation using panel “Miscellaneous Controls” in STAR GUIde. even when a steady state is sought. They may also be functions of the rate of strain tensor’s range II s (see equation (1-5) in Chapter 1 of the Methodology volume).Chapter 3 MATERIAL PROPERTY AND PROBLEM CHARACTERISATION Non-Newtonian Flow stagnation enthalpy relationship rather than the standard enthalpy equation. The appropriate stagnation temperature should then be typed in the Stagnation Temp. The latter contains details of the user input required. pressure and composition. This operation affects only the velocity initialisation. select option Pseudo-Transient from the pop-up menu in the “Solution Method” STAR GUIde panel. Non-Newtonian Flow The theory behind non-Newtonian flow and the manner of implementing it in STAR-CD is given in the Methodology volume (Chapter 16. 5. Setting up non-Newtonian models Step 1 Decide whether the power law offers an adequate representation of the non-Newtonian fluid behaviour and what the value of the constants m and n in equation (1-6) of the Methodology should be. Version 4. they should be allowed for in user subroutine VISMOL. Step 3 Use the “Molecular Viscosity” menu to either specify the model parameters m and n (option NonNewt. over which the equation is fitted.02 3-11 . Alternatively. Step 2 Go to panel “Molecular Properties” in STAR-GUIde and select the domain containing the non-Newtonian fluid via the slider at the bottom of the panel. to do a transient calculation using the “Pseudo-Transient Solution” method. supply a suitable expression in subroutine VISMOL. go to panel “Thermal Models” in STAR-GUIde and select option Stagnation Enthalpy from the Conservation pop-up menu. text box. The latter is applied to the near-wall region where the mesh should be finely spaced.MATERIAL PROPERTY AND PROBLEM CHARACTERISATION Turbulence Modelling Chapter 3 Turbulence Modelling The theory behind the currently available models is given in Chapter 2 of the Methodology manual. For coarser meshes. this is identical to the standard low Reynolds number treatment. The choice of wall treatment (where relevant) is made in the “Near-Wall Treatment” tab of the “Turbulence Models” panel. which offers a special wall treatment for low Reynolds number models independent of the normalised parameter y + . For finely spaced meshes. No special near-wall treatment (other than an optional definition of wall surface roughness) is therefore required. similar to ordinary wall functions (see also Chapter 6. within the boundary layer that forms next to the wall. as shown in Figure 3-3(b). This method employs special algebraic formulae (described in Chapter 6. turbulence parameters. in which viscous effects are incorporated in the k and ε transport equations. etc. Wall functions. 3. turbulence parameters. it provides special algebraic formulae to represent velocity. 3-12 Version 4. temperature. The method is also appropriate for use with one-equation (k-l. you will need to indicate the wall or baffle region to which it applies via the “Define Boundary Regions” panel. provided that a linear k-ε type model is in use and the two treatments are applied to different boundary regions. Hybrid wall boundary condition. “Low Reynolds number turbulence models”. 4. However.02 . see Figure 3-3(a). ‘non-equilibrium’ type of wall function is also provided for taking pressure gradient effects into account (see equation (6-17). An alternative. care must be exercised at transition points between the two methods. k-ω and Reynolds Stress models. Spalart-Allmaras). employed as combinations of a high Reynolds number (k-ε) model with a low Reynolds number (one-equation or zero-equation) model. see also Chapter 6. A number of methods are also available for implementing the no-slip boundary conditions for turbulent flow. temperature. etc. as follows: 1. “Two-layer models” in the Methodology volume. applied to cells immediately adjacent to a wall. Low Reynolds number models. Two-layer models. see also Chapter 6. “High Reynolds number turbulence models and wall functions” of the Methodology volume) to represent velocity. (6-18) and (6-19) in the Methodology volume) but this is available only for k-ε models (linear and non-linear). If a two-layer model is employed. You are free to combine the wall function and two-layer approach within the same problem. 2. Both low Re and wall function treatments may be used in the same problem. “Hybrid wall boundary condition”). but only if they apply to separate domains. Two-layer models 1. as they produce improved friction and heat transfer predictions.e. In general. 3.ε model match location NWL y Low Re model (a) Wall function model (b) Two-layer models Figure 3-3 Mesh spacing in the near-wall region The following points should be borne in mind when considering the effectiveness or accuracy of a particular turbulence model or near-wall treatment: Wall functions 1. This can be achieved by observing the lower limit on the value of y + . In order to resolve properly the distributions of velocity and other variables within the near-wall region (i. The difference between the two is that the latter takes the pressure gradient into account. These should be preferred for non-equilibrium flows.02 3-13 . where: y ≡ ρ Cµ + 1⁄4 1⁄2 k y⁄µ 2. It is important to place y outside the viscous sublayer. it is necessary to ensure that it is spanned by about 15 mesh nodes. the normal distance y from the wall for near-wall cells (see Figure 3-3) should be such that the dimensionless parameter y + is kept within the limits 30 < y + < 100 . Once a suitable mesh density is chosen. at y + ≤ 40 ). For reasons of accuracy. the normal user inputs for wall roughness (specified via the Roughness pop-up menu for wall and baffle boundaries. 4. Their use. see panel “Define Boundary Regions”) are not applicable. since the near-wall region thickness is not known a priori. the value of y + at the Version 4. 2. The above considerations apply equally to both standard and non-equilibrium wall functions. will result in larger meshes within the model and hence significantly higher calculation times.Chapter 3 MATERIAL PROPERTY AND PROBLEM CHARACTERISATION Turbulence Modelling k . this may require some trial and error adjustment of the mesh. This is because the near-wall region requires a finer mesh than that needed by the wall function treatment. This provides more accurate results in terms of wall shear forces but has little effect on the character of the flow. however. If the non-equilibrium option is chosen. cubic and quadratic) (b) k-ω (standard and SST variants) 3-14 Version 4. There is an additional option for fixing the above switching location to its current position. 2. The hybrid wall condition is an extension of low Reynolds number boundary conditions. It applies only to the following low Reynolds number turbulence models: (a) k-ε (linear. It is recommended that such models are run in double precision. 4. where approximately 15 mesh nodes are needed over the near-wall region. their use may require meshes that are even larger than those for the two-layer approach. In such cases. 5. 4. As with two-layer models. the partitioning of the mesh into (a) near-wall region cells where the one-equation model applies (b) other cells in the NWL (c) ordinary cells in the flow field interior can be inspected by opening panel “Load Data” in STAR GUIde (“Data tab”). if required. If the prescribed NWL thickness is not sufficiently large to encompass the near-wall region throughout the domain in question (i. Hybrid wall boundary condition 1. This means that a mesh designed for two-layer models will not necessarily be suitable for low Re models. the switching location there is assumed to be at the edge of the NWL and a warning message is issued on file case. The value of y + at the node next to the wall should then be ~1. the switching location between high and low Re regions shown in Figure 3-3 lies outside the NWL in some places). The default treatment assumes a smooth wall but the wall surface roughness may also be specified.02 . computing times are substantially greater than when using a wall function approach. 3. However. 5. but smaller to resolve the thermal profile. Note that this meshing strategy differs from that for two-layer models. During post-processing. Option FMU allows inspection of the distribution of a quantity given by νt -----------------2 Cµk ⁄ ε Low Re models 1. These should be preferred for non-equilibrium flows. for the same reasons as two-layer models. it is possible to increase the NWL thickness to a more suitable value and restart the calculations. 3. approximately 20 mesh nodes are needed within the near-wall region ( y + ≤ 40 ). If this option is selected from the start of the analysis. In order to resolve properly the distribution of velocity and other variables. choosing “Cell Data” as the data type and then selecting option Two Layer from the Scalar Data scroll list.info.e. its effect is to make the switching point distance equal to the NWL thickness.MATERIAL PROPERTY AND PROBLEM CHARACTERISATION Turbulence Modelling Chapter 3 node next to the wall should be no larger than ~3 to resolve the velocity profile. The ‘standard’ wall reflection term used in the Gibson . The time step size should be selected in such a way that the maximum Courant number does not exceed 0. Version 4. A transient analysis setting is required. whilst being computationally cheaper. Reynolds Stress models 1. the MARS scheme. LES models 1.g. The 3-time-level temporal discretisation scheme within the transient SIMPLE algorithm achieves second-order accuracy. DES models 1. 3. or (b) large variations in y + create uncertainties as to whether a low Reynolds number boundary treatment or a wall function is appropriate. 3. Since Reynolds Stress models solve additional transport equations for Reynolds Stress components. depending on the local flow field and near-wall mesh spacing. It should be preferred in situations where (a) the normalised parameter y + is unknown. the MARS scheme is recommended for the turbulence equations. mixture fractions or enthalpy). although the problem being modelled may in reality be a steady-state one. but may be computationally expensive. Choosing the PISO algorithm results in an accuracy comparable to that of a formally second-order scheme. they consume a substantially greater amount of computing time compared to k-ε models. “Blending Function” in the Methodology volume) is recommended for the discretisation of convective terms in the momentum equation. Choosing the PISO algorithm results in an accuracy comparable to that of a formally second-order scheme. Both the Gibson-Launder and SSG models are high Reynolds number models so they need to be used in conjunction with wall functions. A transient analysis setting is required. In such circumstances. Central differencing or automatic blending (see Chapter 2. 2. 2. it will return the wrong distribution of the stress component normal to the wall. The approach automatically selects a low Reynolds number wall treatment or a wall function. but may be computationally expensive. can be conveniently used for bounded scalars (e.Chapter 3 MATERIAL PROPERTY AND PROBLEM CHARACTERISATION Turbulence Modelling (c) Spalart-Allmaras 2. whilst being computationally cheaper.5. It is therefore advisable to use the term calculated by the Craft model instead. 3. Central differencing is recommended for the discretisation of convective terms in the momentum equation. although the problem being modelled may in reality be a steady-state one.Launder model is not suitable for impingement flows.02 3-15 . The 3-time-level temporal discretisation scheme within the transient SIMPLE algorithm achieves second-order accuracy.5 4. with blending factor not less than 0. 2. k-ε CHEN. The table below illustrates the combinations allowed and the conversion formula adopted when STAR encounters a different turbulence model in the solution file to the one currently in force: FROM (Restart field) SpalartAllmaras k-ε type* k-ω (Wilcox and SST) Reynolds Stress (GL and SSG) 2 V2F SpalartAllmaras k ν t = C µ ---ε 2 k ν t = --ω k k .02 . k-ε Suga Quadratic and Cubic Heat Transfer In Solid-Fluid Systems The theory behind this type of heat transfer models and the manner of implementing it in STAR-CD is given in Chapter 16. The latter contains details of the user input required and important points to bear in mind when setting up problems of this kind. This section contains an outline of the process to be followed when setting up this type of model and includes cross-references to appropriate parts of the STAR GUIde on-line Help system. No special user input is required to run such a case. k-ε RNG. k-ε Quadratic. 3-16 Version 4. “Heat Transfer in Solid-Fluid Systems” of the Methodology volume. k-ε Speziale.MATERIAL PROPERTY AND PROBLEM CHARACTERISATION Heat Transfer In Solid-Fluid Systems Chapter 3 Changing the turbulence model in use This facility allows you to run a turbulent flow case by restarting from a simulation done for the same case but with a different turbulence model.ν t = C µ ---ν t = C µ ---ε ε 2 TO (New solution field) k-ε type* ε = C µ k ω Not needed Not needed k-ω (Wilcox and SST) Reynolds Stress (GL and SSG) ε ω = --------Cµk ε ω = --------Cµk ε ω = --------Cµk Not needed ε = C µ k ω Not needed V2F Not needed ε = C µ k ω Not needed * k-ε. k-ε Cubic. unlike other parts of this region whose default thermal condition is adiabatic. 3) as described in the section on “Cell indexing” on page 3-3. Step 3 Switch on the temperature solver in each fluid material using the “Thermal Models” panel. 2. STAR-CD treats the solid-fluid interface as part of the default wall region (region 0). • STAR uses default expressions to calculate heat transfer (film) coefficients at all solid/fluid interfaces. Step 4 Normally. including those at external walls and baffles. You can supply alternative expressions for these quantities via subroutine MODSWF Step 5 If a printout of temperature distribution in the model is required. Note that this also has the effect of switching on the temperature solver in solid materials. Material 1 — steam Heat flow Material 3 — steel Material 2 — hot gas Figure 3-4 Simple heat exchanger In terms of the heat exchanger example shown in Figure 3-4. the solid-fluid interface is treated as a conducting wall.Chapter 3 MATERIAL PROPERTY AND PROBLEM CHARACTERISATION Heat Transfer In Solid-Fluid Systems Setting up solid-fluid heat transfer models Step 1 Specify the model regions occupied by the solids and fluids present and define their physical properties. use command Version 4. However.02 3-17 • • • . Therefore: If an additional thermal resistance exists at the interface.2 and solid material 3 Assign all cells in the mesh to the appropriate cell type (1. define the latter as a separate region and use the “Define Boundary Regions” panel to specify it as a conducting wall having the required thermal resistance value (see the STAR GUIde “Wall” Help topic for more information). this requires the following actions (see also “Multi-Domain Property Setting” on page 3-5): Set up cell table entries for fluid materials 1. • Specify the physical properties of each material Step 2 Turn on Solid-Fluid Heat Transfer in the “Thermal Options” STAR-GUIde panel. 3-18 Version 4. • The modelling of heat conduction will be slightly in error as a result of the introduction of the above artificial cell shapes.02 • . Thus. “Extrusion” in the Meshing User Guide). Alternative treatment for baffle heat transfer It can be seen that the expansion process described above will create a disturbance in the fluid cells around the baffle and may result in a highly irregular mesh. as shown in the exploded view of the baffle in Figure 3-5. In order to avoid this problem. The surrounding mesh is automatically adjusted to make room for the solid cells. This brings the baffle thickness down to zero and avoids the need to create coupled cells in those parts of the mesh. Heat transfer in baffles Thermal conduction along the plane of a baffle’s surface is currently neglected (see the STAR GUIde “Baffle” Help topic for more information). the fluid flow calculations are based on an undisturbed mesh structure. you need to make sure that the cell type assigned to baffle cells is different from that assigned to solid cells at the base of the baffle. Before After Ordinary baffle Fully-conducting baffle Figure 3-5 ‘Fully-conducting’ baffle creation Note that: Special cell shapes (such as prisms) are created at the edges of the solid cell layer. In the latter case. this effect may still be modelled by expanding a baffle into a single layer of solid cells using command CBEXTRUDE (see also Chapter 2. • A baffle of the kind described here may be attached directly to an external boundary or to internal boundaries such as solid-fluid interfaces to model a conducting fin. However. as shown in Figure 3-5. a facility is provided for specifying a finite baffle thickness (to be used internally for heat conduction calculations) but without actually expanding the baffle to that thickness.MATERIAL PROPERTY AND PROBLEM CHARACTERISATION Heat Transfer In Solid-Fluid Systems Chapter 3 PRTEMP to specify whether the printed values are absolute or relative to the datum temperature previously defined (see topic “Reference Data” in the STAR GUIde on-line Help system). Step 4 Go back to the Cell Table Editor and select the solid cell type defined in Step 1. the default wall boundary condition for region number 0 will be used. Conducting baffles that have a different DT or different Conduction Thickness must also have a different cell type. even if the entire model is made up of solid cells. Enter the actual conduction thickness in the box labelled Conduction Thickness Step 5 Turn on Solid-Fluid Heat Transfer in the “Thermal Options” STAR-GUIde panel. no-slip wall. • If no solid cell thickness. This results in a conducting. Step 3 Apply command CBEXTRUDE to the baffle cells created in Step 2 and extrude them into solid cells using the solid cell type created in Step 1. DT. The latter will be used to represent the ‘conducting baffles’. The On button in the Solid-Fluid Heat Transfer section of the “Thermal Options” STAR-GUIde panel must always be used to turn on the solution of the energy equation in solids. 2. Step 6 Apply the appropriate wall boundary condition to the solid cells created in Step 3.Chapter 3 MATERIAL PROPERTY AND PROBLEM CHARACTERISATION Heat Transfer In Solid-Fluid Systems To use this facility. Step 2 Create the baffle cells in the appropriate mesh location using the baffle cell type defined in Step 1.2 × 10-3 m. create a separate baffle cell type and a separate solid cell type. A conducting baffle that is attached to a solid base must have a different cell type to that of the solid to which it is attached. • If no solid cell type identification. is supplied in the CBEXTRUDE command (this is the normal practice). Note that: • Conducting baffles of the same thickness DT specified in command CBEXTRUDE and of the same Conduction Thickness specified in the Cell Table Editor can share the same cell type. The Version 4. is supplied in the CBEXTRUDE command. This helps to overcome potential convergence problems arising as a result of a large disparity in thermal conductivity between fluid and solid. the baffle cells will be removed from the mesh and replaced by the solid cells that they have been extruded into. the solid cell identification will be set as cell type 1. It is usually advisable to run solid-fluid heat transfer simulations in double precision. • • • Useful points on solid-fluid heat transfer 1.02 3-19 . the default thickness will be applied. If none is specified. currently set at 0. ICTID. the following steps are needed: Step 1 Using the Cell Table Editor. Note that: Upon extrusion. 0 to aid convergence.02 . you will need to match cells on either side of the interface.MATERIAL PROPERTY AND PROBLEM CHARACTERISATION Buoyancy-driven Flows and Natural Convection Chapter 3 3. If your model contains an arbitrary or embedded mesh interface between the fluid and solid cells. 6. 5.0. The present chapter contains an outline of the process to be followed when setting up buoyancy-driven flows and includes cross-references to appropriate parts of the STAR GUIde on-line Help system. “Buoyancy-driven Flows and Natural Convection”). Check the settings in STAR GUIde’s “Gravity” panel (which determine the 3-20 Version 4. Step 6). Setting up buoyancy-driven models Step 1 Switch on the temperature solver using the “Thermal Models” STAR-GUIde panel Step 2 Switch on the density solver by selecting one of the following options from the “Density” pop-up menu in the “Molecular Properties” panel: • Isobaric — isobaric density variation (normally used for liquids) • Ideal-f(T) — density variation based on the Ideal Gas Law • User-f(T) — density variation based on user-defined relationships Step 3 Set up the problem’s initial conditions using the “Initialisation” panel controls Step 4 Define the reference pressure and temperature plus the reference pressure cell location using the “Monitoring and Reference Data” panel Step 5 Use the “Buoyancy” panel to specify suitable buoyancy parameters for your problem. as described in Chapter 3. The latter contains details of the user input required and important points to bear in mind when setting up problems of this kind. choice of single or double precision mode can be made when running STAR (see Chapter 2. we recommend that the corresponding factor for solids is left at 1. “Couple creation” in the Meshing User Guide. Useful points on buoyancy-driven flow 1. In some situations the energy under-relaxation factor in fluid domains has to be reduced below its default value of 1. A convenient way of modelling thermal contact resistance between two adjacent solid domains is to define a baffle of suitable properties at the faces of the appropriate solid cells in one of the domains. “Running a STAR-CD Analysis”. 4. If your model contains scalar variables. the only valid scalar boundary condition for walls located at the solid-fluid interface is Adiabatic. Buoyancy-driven Flows and Natural Convection The theory behind flow problems of this kind and the manner of implementing it in STAR-CD is given in the Methodology volume (Chapter 16. In such cases. Also note that. if one exists. A method of calculating the time step size is given in the Methodology volume (Chapter 16.9. The consequences of working in single precision mode are oscillation in the residual values and non-convergence of the solution.Chapter 3 MATERIAL PROPERTY AND PROBLEM CHARACTERISATION Fluid Injection gravitational body force effects) before starting a buoyancy calculation. If convergence problems are encountered. It is therefore advisable to use the PISO algorithm which is more suitable for this type of coupling. In multi-domain problems. “Buoyancy-driven Flows and Natural Convection”). 6. since this way one does not need to set up load steps. 5. This measure often helps to stabilise the solution and promote convergence.e. if droplets and/or liquid wall films are present in your model. If you use the option for direct specification of the reference density. This involves approaching the steady-state solution. the reference density and datum location should be defined domain-wise. Buoyancy-driven flows with high Grashof number (i. In problems of this type. it may be necessary to run the model in transient mode. The most convenient way of doing this is to use the single-transient solution mode (see Chapter 5. “Default (single-transient) solution mode”). In such cases. 8. “Local Fluid Injection/Extraction”). 4. 7.e. there is very strong coupling between the temperature.g. Fluid Injection The theory behind flow problems of this kind and the manner of implementing it in STAR-CD is given in the Methodology volume (Chapter 16. scalar mass fraction and flow fields. The desired values may be entered in the corresponding Relaxation Factor boxes inside panel “Solver Parameters” in STAR GUIde. It is usually advisable to run buoyancy-driven flow simulations in double precision. This section contains an outline of the process to be Version 4. The choice of single or double precision mode can be made when running STAR (see Chapter 2. For simulations without pressure boundaries: (a) In steady-state calculations.02 3-21 . time-dependent without a single unique solution). a converged steady-state solution cannot be obtained and you should opt for the transient approach. Gr > 109) are sometimes naturally unstable (i. gravitational effects for these features must be switched on separately. If convergence problems are encountered. (b) In transient calculations. Step 6). This can cause delay in the solution convergence. “Running a STAR-CD Analysis”. by means of time steps. 2. the latter should be assigned a realistic value based on the expected density variation in the fluid. This is because the body force terms in the momentum equation are often so small compared to the other terms that they can be masked by the round-off error of the calculation. unrealistic values can give rise to a body force that is out of balance with the piezometric pressure gradient. it is advisable to begin the calculations with a small amount of under-relaxation on both temperature and density. e. these initial disturbances could also produce unrealistic initial fields and therefore invalidate the results of the analysis. 3. 0. Also included are crossreferences to appropriate parts of the on-line Help system. Step 3 Copy subroutine FLUINJ into the ufile sub-directory of your working directory. the code specifies the mass flux injected or removed (on a per unit volume basis) for cells of the required type. it is assumed that the fluid is bringing all its properties into the computational domain). Thus. If mass is being injected. you may need to calculate this volume first. temperature and chemical species mass fractions.e. as described in Chapter 14. ε). either by choosing Utility > Calculate Volume > Cell Set from pro-STAR’s main menu bar or by using command VOLUME. Usually. Step 4 Insert appropriate code in subroutine FLUINJ using a suitable editor. specify all relevant properties of the incoming fluid (i. containing details of the user input required. only the mass flux needs to be specified as the withdrawn fluid is assumed to possess the (known) properties in its vicinity. If only the total amount of mass injected is known. Setting up fluid injection models Step 1 Create a set of all cells where fluid injection or removal is to be take place.MATERIAL PROPERTY AND PROBLEM CHARACTERISATION Fluid Injection Chapter 3 followed when setting up fluid injection problems. so that a single value can be used for the entire cell set selected. A separate cell table index number should be assigned to this set (see “The Cell Table” on page 3-1). W). Step 2 Activate the injection facility using the “Mass” tab in STAR-GUIde’s “Source Terms” panel. “Subroutine Usage”. If mass is being removed. An example of this is given in the sample coding supplied in subroutine FLUINJ. the required value may be obtained by dividing by the total volume of the cell set. turbulence parameters (k. The properties in question may be velocity components (U. V.02 . 3-22 Version 4. Specify the conditions at the boundaries (i. In the example shown in Figure 4-2. Identify the location of individual. The indexing of boundary cell faces (or boundaries. (b) solid/fluid interface boundaries in heat transfer problems. except for: (a) so-called baffle boundaries. A boundary region consists of a group of cell faces that cover the desired boundary surface. Figure 4-1 shows a boundary region made up of nine cell faces. They are created on the outer surfaces of the mesh.Chapter 4 BOUNDARY AND INITIAL CONDITIONS Introduction Chapter 4 BOUNDARY AND INITIAL CONDITIONS The process of defining boundaries in a model can be divided into two major steps: 1. in a similar manner to the automatic cell numbering discussed in “Cells” on page 2-37 of the Meshing User Guide. Figure 4-1 Boundary region definition The rules governing the use of boundary regions are as follows: • • Regions are numbered in an arbitrary manner by the user. what the conditions are). 1 to 9 are assigned to region 1. which are normally positioned at the interface of two cells.e. boundary nos. 4-1 Version 4. in order to identify them. Users should have a good understanding of the physical significance and numerical implications of different boundary conditions and should apply them correctly to their model. since the outcome of the simulation depends on them.02 . for short) comprising a region is done automatically by pro-STAR. It is of the utmost importance that boundaries are chosen and implemented correctly. Introduction Boundary Location The two important geometrical features of boundaries are: 1. They are grouped into boundary regions. where the boundaries are). distinct boundaries (i.e. 2. 2. It is therefore advisable to refer to the relevant sections of the Methodology volume for guidance. The same operation can also be executed by choosing Utility > Count > Boundaries from the menu bar. Re-assignment of a boundary to a different region graphically — command BCROSS. pro-STAR offers two methods for setting up boundary regions: 1. cell number and cell face number on which the boundary will be created.02 . • • • • • For further details on the function and application of boundary commands. pro-STAR generates the boundary number automatically.BOUNDARY AND INITIAL CONDITIONS Boundary Location Chapter 4 7 4 1 8 5 2 9 6 3 Figure 4-2 Boundary cell face indexing Thus. as described below 2. This creates additional boundaries by applying an offset to the cell numbers of a previously-defined set. Using the facilities of panel “Create Boundaries” in STAR GUIde (“Regions” tab) Command-driven facilities The available functions are as follows: • Assignment of boundaries to a region using the keyboard — command BDEFINE. Conversion of a set of shells into a set of boundaries — command BSHELL. 4-2 Version 4. Counting the currently defined boundaries — command COUNT. Typing commands from the keyboard. refer to the pro-STAR Commands volume. each boundary in the model is identified by a region number (user-defined) and composed of boundary cell faces that are automatically numbered by pro-STAR. The starting shells are not deleted by this process. using command BGENERATE. This requires input of the region number. Further boundaries can be created individually or generated from an existing set. Modification of the region number assigned to a boundary face — command BMODIFY. Chapter 4 BOUNDARY AND INITIAL CONDITIONS Boundary Location Boundary set selection facilities Boundaries may need to be grouped together for the purposes of mass manipulation or plotting, thus defining a boundary set. This is done by selecting one of the list options provided by the B-> button in the main pro-STAR window. The available options are: 1. All — puts all existing boundaries in the current set 2. None — clears the current set 3. Invert — replaces the current set with one consisting of all currently unselected boundaries 4. New — replaces the current set with a new set of boundaries 5. Add — adds new boundaries to the current set 6. Unselect — removes boundaries from the current set 7. Subset — selects a smaller group of boundaries from those in the current set For the last four options, the required boundaries are collected by choosing an item from a secondary drop-down list, as follows: • • Cursor Select — click on the desired boundaries with the cursor, complete the selection by clicking the Done button on the plot Zone — use the cursor to draw a polygon around the desired boundaries. Complete the polygon by clicking the right mouse button (or the Done button outside the display area to let pro-STAR do it for you). Abort the selection by clicking the Abort button. Region (Current) — select all boundaries whose region number is currently highlighted in the boundary region table Region (Cursor Select) — select all boundaries belonging to a given region. The required region is selected by clicking on a representative boundary with the cursor. Patch (Cursor Select) — select all boundaries containing radiation patches (see Chapter 7, Step 6). The patches in question are selected by clicking with the cursor. Vertex Set (All) — all constituent vertices of the selected boundaries must be in the current vertex set Vertex Set (Any) — the selected boundaries must have at least one constituent vertex in the current vertex set Attach, Baffle, Cyclic, Degas (Phase Escape boundary condition used in Eulerian multi-phase problems), Freestream, Inlet, Monitoring, NonReflective_Pressure, NonReflective_Stagnation, Outlet, Pressure, Radiation, Riemann, Stagnation, Symplane, Transient, Wall — all boundaries must be of the type selected, regardless of region number More boundary set operations are available in the Boundary List dialog (see “Boundary listing” below) or by typing command BSET (see the pro-STAR Commands volume for a description of additional selection options). Boundary listing Boundary information is displayed in the Boundary List dialog shown below, obtained by selecting Lists > Boundaries from the main menu bar. Boundary definitions are displayed in a scroll list in numerically ascending order, in terms of: Version 4.02 4-3 • • • • • • BOUNDARY AND INITIAL CONDITIONS Boundary Location Chapter 4 • • • • • • Boundary serial number Parent cell serial number Face number of this cell that has been defined as a boundary Patch serial number of any radiation patch that has also been created on that face Region number Boundary type There is also a choice of listing all boundaries or just the current set (marked by asterisks in the Bset column). The choice is made by simply selecting the Show All Boundaries or Show Bset Only option, respectively. To select boundaries from the list: • • For single items, click the number of the required boundary. For two or more items in sequence, click the first boundary you want to select, and then press and hold down the Shift key while you click the last boundary in the group. Commands: BLIST BDELETE BMODIFY BSET Once the desired boundaries are selected, the following additional operations are possible: 1. Addition to (or removal from) the current set — click the Add to Set/Remove from Set button. 2. Deletion — click the Delete Boundary button. 3. Change of boundary region — click the Change Region button. This activates an additional dialog, shown below. To change the region type associated with the selected boundaries, choose a different region number on the displayed Change Region box and then click the Apply button. 4-4 Version 4.02 Chapter 4 BOUNDARY AND INITIAL CONDITIONS Boundary Region Definition Note that all the above operations have an immediate effect on the boundary definitions, reflected by immediate changes to what is displayed in the list. However, any subsequent boundary changes made outside this dialog, e.g. by issuing commands via the pro-STAR I/O window, will not be listed. To display these changes, click Update List at the top of the dialog. Boundary Region Definition Having specified the location of all boundaries in the model, the next step is to • • define their individual type (i.e. set the boundary condition); supply information relevant to that type. The boundary types available at present are: 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 17. Inlet Outlet Pressure Non-reflective pressure Stagnation Non-reflective stagnation Wall Baffle Symmetry plane Cyclic Free-stream transmissive Transient-wave transmissive Riemann Invariant Attachment Radiation Monitoring Phase-escape (Degassing) The extent of the information required to define each boundary properly depends in many cases on the variables being solved. For example, in problems using the k-ε model, an inlet boundary needs information concerning the turbulence quantities k and ε. In most cases, the appropriate variables are activated automatically as a result of choosing a given modelling option, e.g. Version 4.02 4-5 BOUNDARY AND INITIAL CONDITIONS Boundary Region Definition Chapter 4 • • In the “Molecular Properties” STAR GUIde panel, the ideal gas option for density will switch the density solver on In the “Turbulence Models” panel, any of the K-Epsilon options will switch on the k, ε and viscosity solver Note that: 1. In the case of a variable such as temperature, you need to switch on the temperature solver explicitly (in panel “Thermal Models”) before proceeding with region definitions. 2. Specification of alternative sets of variables needed to completely define boundaries of type ‘Inlet’ or ‘Pressure’ is possible, as discussed in the sections dealing with such boundaries. 3. It is possible to check for common mistakes in prescribing boundary conditions (e.g. boundary velocities specified in an undefined local coordinate system) by using the facilities available within the “Check Everything” STAR-GUIde panel. 4. Boundary regions may be given an optional alphanumeric name to help distinguish one region from another more easily. The easiest way of applying a desired boundary condition to a given region is via the STAR GUIde system; go to the Define Boundary Conditions folder and open the “Define Boundary Regions” panel, as in the example shown below: The number and purpose of the text boxes appearing in the panel and whether they are active or not depends on • • 4-6 the type of condition selected; which variables are being solved for. Version 4.02 Chapter 4 BOUNDARY AND INITIAL CONDITIONS Boundary Region Definition On the other hand, all forms of the panel possess a number of common features, listed below: 1. New regions are defined by: (a) Selecting an unused region in the boundary regions scroll list (b) Choosing the desired boundary condition via the Region Type menu options. The effect of this is to immediately display input boxes for supplying boundary values for all flow variables required. (c) Typing an optional name in the Region Name text box 2. Modification of existing regions is performed in a similar way. The changes are made permanent by clicking the Apply button. 3. Additional boundary regions with identical properties to a pre-defined base region set may also be generated by typing command RGENERATE in the pro-STAR I/O window. 4. Selected region definitions can be deleted by clicking Delete Region. 5. The Compress button eliminates all deleted or undefined regions from the boundary regions scroll list and renumbers the remaining ones contiguously. 6. All free surfaces in your model that are neither defined as boundaries nor explicitly assigned to a region will become part of region no. 0 (shown in the example above). The latter’s properties may be specified in the same way as for any other region. By default, this region is assumed to be a smooth, stationary, impermeable, adiabatic wall. 7. Non-uniform or time-varying conditions may be specified for some boundary types. This is done by choosing one of the following from the Options menu (the default setting, Standard, means constant and uniform conditions): (a) User — specify the required conditions in one of the user subroutines listed below (see also Chapter 14): i) ii) iii) iv) v) vi) vii) viii) ix) x) BCDEFI — Inlet BCDEFO — Outlet BCDEFP — Pressure BCDNRP — Non-reflective pressure BCDEFS — Stagnation BCDNRS — Non-reflective stagnation BCDEFW — Wall or Baffle BCDEFF — Free-stream transmissive BCDEFT — Transient-wave transmissive BCDEFR — Riemann invariant The panel also displays a Define user coding button. Click it to store the default source code in sub-directory ufile, ready for further editing. (b) Table — use values stored in a table file as boundary conditions. The file name is of form case.tbl (see Chapter 2, “Table Manipulation”) and may be entered in the Table Name text box. Alternatively, the file may be selected using pro-STAR’s built-in browser. Note that whilst one table can be applied to multiple boundary regions, multiple tables cannot be applied to the same boundary region. A list of Version 4.02 4-7 BOUNDARY AND INITIAL CONDITIONS Boundary Region Definition Chapter 4 valid dependent variable names that may be used in tables is given for each boundary type in the sections that follow. In addition, the coordinate system used in a table must be the same as the coordinate system specified for its associated boundary regions. Table values are actually assigned to a boundary by the STAR-CD solver during the analysis. This is done as follows: i) Table data are mapped onto the appropriate boundary region in the mesh ii) Boundary face-centre coordinates are compared with the table coordinates iii) Variable values at face centres are calculated from the table data using inverse distance-weighted interpolation iv) The resulting values are assigned to the boundary for the whole duration of the analysis Figure 4-3 shows an example of using a table to assign boundary conditions to a computational boundary. The coordinates and user-supplied values are stored at the nodes of the table data grid and the STAR flow variables are stored at the boundary face centres. In the example, boundary values at face centre 1 are calculated as a weighted average of the table data located at ABCD. Similarly, values at face centre 2 are a weighted average of the table data located at EFGH. Table data map Boundary mesh Table data node B A 1 F 2 G H E Boundary face centre C D Figure 4-3 Mapping and interpolation of table data onto a boundary Please also note the following: i) It is possible to produce contour or vector plots of the boundary conditions specified by the table, as a means of checking that the table values have been entered correctly. To do this, click Plot Boundary after you have read in the table and then specify which flow variables you wish to plot. 4-8 Version 4.02 Chapter 4 BOUNDARY AND INITIAL CONDITIONS Inlet Boundaries ii) The use of boundary condition tables is not supported for cases using the load-step method to define transient conditions (see Chapter 5, “Load-step based solution mode”) (c) GT-POWER — set up a link with the GT-POWER engine system simulation tool (see Chapter 11 of the Supplementary Notes). This provides automatic updating of boundary conditions at inlet and/or pressure boundaries during engine simulation runs. Note that this facility becomes active only after the relevant option has been selected in the “Miscellaneous Controls” panel. (d) Rad. Eq. Tip — impose a radial equilibrium condition by specifying the static pressure at the tip of a turbomachinery case. (e) Rad. Eq. Hub — impose a radial equilibrium condition by specifying the static pressure at the rotor hub of a turbomachinery case. Inlet Boundaries Introduction This condition describes an inflow boundary and thus requires specification of inlet fluxes for • • • • • mass momentum turbulence quantities energy chemical species mass fraction as appropriate. The same boundary type may also be used to specify an outflow condition (i.e. ‘negative inlet’). Note that boundary values are needed only for variables pertinent to the problem being analysed (see “Boundary Region Definition” on page 4-5). In specifying turbulence quantities, it is possible to select in advance the form in which the required boundary values will be input. It is also possible to specify how mass influx is treated under subsonic compressible flow conditions. The choices are made in the “Define Boundary Regions” panel for inlets, as shown in the example below, and are fully described in the “Inlet” on-line Help topic. Version 4.02 4-9 BOUNDARY AND INITIAL CONDITIONS Inlet Boundaries Chapter 4 Useful points 1. If the Flow Switch and Turb. Switch settings are changed after velocity components and turbulence boundary conditions have been input, the existing values are not converted in any way, but are interpreted differently. You should therefore use “Define Boundary Regions” to correct these values. 2. Boundary values for turbulence in domains using a Reynolds Stress model may be specified solely in terms of k and ε instead of Reynolds Stress components. If this option is chosen, turbulence conditions at the boundary are assumed to be isotropic. 3. At negative inlets, i.e. inlet boundaries with velocity components pointing out of the solution domain, values for temperature, turbulence quantities and chemical species mass fractions are ignored. 4. Special considerations apply to tetrahedral meshes or meshes containing trimmed (polyhedral) cells. If such meshes contain supersonic inlet boundaries then, to obtain a stable/convergent solution, it is necessary to create at least two cell layers immediately next to the boundary (see Figure 4-5 on page 4-23). If pro-STAR’s automatic meshing module is employed for this purpose, use its built-in mesh generation capabilities. If the mesh is imported from a package that lacks these facilities, you must extrude the mesh in a direction normal to the boundary and then shift the boundary location to the edge of the newly-created, layered structure. 5. If boundary conditions are set using a table (see page 4-7), the permissible variable names that may appear in the table and their meaning is as follows: (a) U — U-component of velocity 4-10 Version 4.02 02 4-11 . use the scalar species name. Prescribed flow split boundary. i.g. 6. Inlet boundaries should only be placed on the external surfaces of a fluid domain.. as the scalar variable name(s) You must also ensure that the coordinate system used is the same as the coordinate system specified in the “Define Boundary Regions” panel. ∑ fs = 1 (4-1) (c) This type of boundary must not be used in combination with a pressure or a stagnation pressure boundary within the same fluid domain. This applies to all methods of boundary condition input. User coding or Table.Reynolds stress component (j) VW . N2 etc.Reynolds stress component (l) T — Temperature (absolute) (m) DEN — Density (n) Scalar_name — Mass fraction. 7. e. i. There are two types of outlet boundary: 1.e.e.Chapter 4 BOUNDARY AND INITIAL CONDITIONS Outlet Boundaries (b) V — V-component of velocity (c) W — W-component of velocity (d) TE — Turbulence kinetic energy or intensity. (a) The specified outflow rate m (b) This type of boundary must be used in combination with at least one Version 4. (b) Flow splits for all outlet regions belonging to a given fluid domain should sum to unity. H2O. depending on the Turb. The conditions that must be observed in this case are: ˙ out must be positive. compressible flow case in which the mass flux is to be maintained at a constant value (the Flow Switch menu setting is Mass Flux). Switch setting (e) ED — Turbulence kinetic energy dissipation rate or length scale.Reynolds stress component (k) UW . Standard STAR GUIde panel entry. (d) This type of boundary must not be used for transient compressible flow cases 2.Reynolds stress component (g) VV . Outlet Boundaries Introduction This condition should be applied at locations where the flow is outwardly directed but the conditions are otherwise unknown. you must specify both velocity components and density as inlet conditions. Prescribed mass outflow rate boundary. When running a transient. The conditions that must be observed are: (a) The specified split factor f s must be positive. depending on the above setting (f) UU .Reynolds stress component (h) WW .Reynolds stress component (i) UV . BOUNDARY AND INITIAL CONDITIONS Pressure Boundaries Chapter 4 pressure boundary. Outlet boundaries should only be placed on the external surfaces of a fluid domain. If boundary conditions are set using a table (see page 4-7). whereas the latter prescribes only the mass rate. For solution stability and accuracy. The meaning of this variable is either flow split or mass outflow rate.02 . 6. 5. is allowed. etc. 3. where it is reasonable to expect true outflow everywhere on the boundary. only one variable name FSORMF. Useful points 1. For turbomachinery cases. The desired boundary type is imposed via the “Define Boundary Regions” panel for outlets. outlet boundaries should be used only far downstream of strong recirculation areas. Prescribed mass outflow boundaries are recommended for obtaining fully developed flow in pipes. and is fully described in the “Outlet” on-line Help topic. 4. 2. as shown in the example below. The difference between outflow conditions described using negative inlet as opposed to prescribed mass outflow boundaries is that the former prescribes both the velocity distribution as well as the mass rate. Note that the variable must be a function of time only. Pressure Boundaries Introduction This condition specifies a constant static pressure or piezometric pressure on a given boundary. Outlet boundaries are incompatible with: (a) Transonic flows (b) Cavitating flows 7. depending on the Condition pop-up menu setting described above. channels. it is also possible to specify the static pressure at the tip or hub and impose a pressure distribution that satisfies radial 4-12 Version 4. Outlet boundaries of the two basic types described above must not coexist in the same domain. However. as shown in the example below. For example. 4. if the model contains two boundaries at 10 and 11 bars a reasonable reference pressure would be 10 Version 4. Analyses with multiple pressure boundaries inherently converge more slowly than those where the inlet flow rates and flow splits have been specified. temperature. it is possible to select in advance the way in which these quantities will be determined. mass fraction or (optional) tangential velocity components. and are fully described in the “Pressure Boundary” on-line Help topic. the values are obtained from the supplied boundary conditions. 2.02 4-13 . The direction and magnitude of the flow are determined as part of the solution. For a given fluid domain. • • if the flow is directed outwards. The choices are made in the “Define Boundary Regions” panel for pressure boundaries. 3. if the flow is directed inwards. Thus. any such conditions are only applied if the flow direction is towards the solution domain interior. the values of the other variables are extrapolated from the upstream direction. It is advisable to choose a reference pressure that is of the same order as the pressure values on the boundaries. pressure boundaries must not coexist with outlet boundaries of the ‘Flow Split’ type. Numerical instability may occur when large or curved surfaces are used as pressure boundaries. Useful points 1. In specifying turbulence quantities.Chapter 4 BOUNDARY AND INITIAL CONDITIONS Pressure Boundaries equilibrium. the permissible variable names that may appear in the table and their meaning is as follows: (a) (b) (c) (d) (e) PR — Pressure (relative) TE — Turbulence intensity ED — Turbulence length scale T — Temperature (absolute) Scalar_name — Mass fraction. bars.02 . 12. Information relevant to such a region is supplied in the “Define Boundary Regions” panel for stagnation boundaries. it is recommended that the user supplies an estimate for the maximum velocity within the solution domain in the relevant text box of the “Initialisation” panel (see also “Solution Domain Initialisation” on page 4-42). When option Mean On is used (see the “Pressure Boundary” STAR GUIde panel). explicit velocity specification. 6. as the scalar variable name(s) 11. If boundary conditions are set using a table (see page 4-7). It normally appears in compressible flow calculations. but you may also employ it for incompressible flows. but not spatial variations. the scope for tabular input of pressure is limited. see the “Pressure Boundary” STAR GUIde panel) is recommend. the values already supplied are ignored. H2O. This practice will help to avoid start-up difficulties and to minimise problems due to machine round-off errors. Stagnation Boundaries Introduction This condition is typically used on a boundary lying in a large reservoir where fluid properties are not significantly affected by flow conditions in the solution domain. N2 etc. 8. use of the UVW On option (i. use the scalar species name. In cases where a pressure boundary coexists with another pressure or stagnation boundary. 7.BOUNDARY AND INITIAL CONDITIONS Stagnation Boundaries Chapter 4 5. Any type of mesh may be used for problems containing radial equilibrium boundaries but only one such region must be employed in the model. as shown in the example below.g. you must ensure that the datum level location and density (as specified in the “Buoyancy” panel) are for a point lying on the pressure boundary itself. Temporal variations in pressure may be prescribed through tabular input. If the Turb. 9. If the piezometric setting is chosen for problems involving buoyancy driven flow. Switch setting is changed to Zero Grad after turbulence boundary conditions have been input. To obtain a stable/convergent solution for tetrahedral meshes or meshes containing trimmed (polyhedral) cells. e.e. the user may change the number of averaging intervals to capture the problem details more accurately. 4-14 Version 4. 10. Pressure boundaries should only be placed on the external surfaces of a fluid domain. and is described in the “Stagnation Boundary” on-line Help topic. The default interval value (50) is however adequate for most cases. Note also that in cases of high circumferential velocity gradients in the radial direction. turbulence conditions at the boundary are assumed to be isotropic. 5. use its built-in mesh generation capabilities. To obtain a stable/convergent solution for tetrahedral meshes or meshes containing trimmed (polyhedral) cells. This will ensure that the calculations start with a reasonable initial velocity field. 6. 3. stagnation boundaries must not co-exist with outlet boundaries of the ‘Flow Split’ type. you must extrude the mesh in a direction normal to the boundary and then shift the boundary location to the edge of the newly-created. If the mesh is imported from a package that lacks these facilities. layered structure. It is recommended that the user supplies an estimate for the maximum velocity within the solution domain via the relevant text box of the “Initialisation” panel (see also “Solution Domain Initialisation” on page 4-42). 2. Stagnation boundaries are incompatible with: (a) Eulerian multi-phase flows Version 4.Chapter 4 BOUNDARY AND INITIAL CONDITIONS Stagnation Boundaries Useful points 1. If pro-STAR’s automatic meshing module is employed for this purpose. 4. If a fluid domain contains a stagnation boundary. it is necessary to create at least two cell layers immediately next to the boundary (see Figure 4-5 on page 4-23). If this option is chosen. For a given fluid domain.02 4-15 . Boundary values for turbulence in domains using a Reynolds Stress model may be specified solely in terms of k and ε instead of Reynolds Stress components. it must also contain a pressure boundary. 02 . N2 etc.BOUNDARY AND INITIAL CONDITIONS Non-reflective Pressure and Stagnation Boundaries Chapter 4 (b) Free surface flows (c) Cavitating flows 7. 8. If boundary conditions are set using a table (see page 4-7). 4-16 Version 4. Furthermore. as the scalar variable name(s) You must also ensure that the coordinate system used is the same as the coordinate system specified in the “Define Boundary Regions” panel.g. Switch setting (h) Scalar_name — Mass fraction. It may only be used in situations where the working fluid is an ideal gas and the flow is compressible. it requires the presence of periodic (cyclic) boundaries in a transverse direction relative to the dominant flow direction. depending on the Turb. Stagnation boundaries should only be placed on the external surfaces of a fluid domain. Non-reflective Pressure and Stagnation Boundaries Introduction This type of boundary condition was specially developed for turbomachinery applications. Switch setting (g) TLSCB — Turbulence kinetic energy dissipation rate or length scale. as illustrated in Figure 4-4 below. depending on the Turb. e. use the scalar species name. the permissible variable names that may appear in the table and their meaning is as follows: (a) (b) (c) (d) (e) (f) DCX — Direction cosine for U-component of velocity DCY — Direction cosine for V-component of velocity DCZ — Direction cosine for W-component of velocity PSTAGB — Stagnation pressure (relative) TSTAG — Stagnation temperature (absolute) TINTB — Turbulence kinetic energy or intensity. H2O. Version 4. The relevant form of this panel for non-reflecting stagnation boundaries is shown in the example below and is fully described in the “Non-reflective Stagnation Boundary” on-line Help topic.02 4-17 . The information required for each type represents the average value of the dependent variables that need to be satisfied by the simulation and is supplied in the “Define Boundary Regions” panel.Chapter 4 BOUNDARY AND INITIAL CONDITIONS Non-reflective Pressure and Stagnation Boundaries Circumferential direction Wall Cyclic boundary Flow (axial) direction Cyclic boundary Wall Figure 4-4 Example of non-reflecting boundary mesh structure Boundaries of this kind are frequently used as non-reflective pressure/stagnation pairs. The minimum number is 0. these regions can have the same boundary conditions. For a given fluid domain. 4. 5. aligned along the circumferential direction as shown in Figure 4-4. 8.BOUNDARY AND INITIAL CONDITIONS Non-reflective Pressure and Stagnation Boundaries Chapter 4 The panel for a non-reflecting pressure boundary is shown below and is fully described in the “Non-reflective Pressure Boundary” on-line Help topic. This can then be followed by a restart run where the non-reflecting boundaries have been applied. non-reflective boundaries must not coexist with outlet boundaries of the ‘Flow Split’ type. 3. certain physical features must not be present in cases containing non-reflective boundaries. Useful points 1. The boundary surface must be delimited by cyclic boundaries along the transverse direction. At present. it may be necessary to start the simulation by using standard pressure and stagnation boundary conditions over a number of iterations. the maximum number of harmonics to be used by the Discrete Fourier Transform algorithm is N/2 -1.02 . If N is the number of cells along the circumferential direction. Such conditions cannot be assigned to boundary region no. The excluded features are: (a) (b) (c) (d) (e) 4-18 Transient calculations Chemical reactions and scalar variables Radiation Reynolds Stress and V2F turbulence models Two-phase flow Version 4. Each strip of boundary faces along the circumferential direction must be assigned to a different non-reflective region number. 7. (b) The cell layer adjacent to the boundary must contain only hexahedral cells 2. However. To ensure that the analysis runs smoothly. 0. as shown in Figure 4-4. 6. Non-reflective pressure and stagnation conditions impose a number of restrictions on the type of mesh employed at the boundary surface: (a) The boundary must contain only quadrilateral faces. Moving or stationary. Smooth or rough. Non-reflective boundaries should only be placed on the external surfaces of a fluid domain. If boundary conditions are set using a table (see page 4-7). depending on the Turb. If motion normal to that surface is desired. use the moving mesh features discussed in Chapter 12. a wall boundary may be defined as: • Of the no-slip or slip type. “Turbulence Modelling”. depending on the above setting The user must also ensure that the coordinate system used is the same as the coordinate system specified in the “Define Boundary Regions” panel. Permeable or impermeable to heat and/or mass flow. 10. A wall may move within the surface it defines. the permissible variable names that may appear in the table and their meaning is as follows: (a) Non-reflective pressure boundaries i) PR — Pressure (relative static) ii) TE — Turbulence kinetic energy or intensity. 4-19 • • • • • Version 4. Switch setting iii) ED — Turbulence kinetic energy dissipation rate or length scale. Thus. The no-slip boundary conditions for turbulent flow are implemented using one of the methods discussed in Chapter 3.Chapter 4 BOUNDARY AND INITIAL CONDITIONS Wall Boundaries (f) Moving meshes (g) Liquid films (h) Free surface and cavitation 9. Switch setting vii) TLSCB — Turbulence kinetic energy dissipation rate or length scale. depending on the Turb. The latter is applicable to inviscid flows (in practice µ is set to 10–30 Pa s). “Moving Meshes”. depending on the above setting (b) Non-reflective stagnation boundaries DCX — Direction cosine for U-component of velocity DCY — Direction cosine for V-component of velocity DCZ — Direction cosine for W-component of velocity PSTAGB — Stagnation pressure (relative) TSTAG — Stagnation temperature (absolute) TINTB — Turbulence kinetic energy or intensity. Resistant or not to heat flux due to a thermal boundary layer or intervening solid material. i) ii) iii) iv) v) vi) Wall Boundaries Introduction STAR-CD’s implementation of wall boundaries involves a generalisation and extension of the no-slip and impermeability conditions commonly used at such surfaces. Radiating or non-radiating (see also Chapter 7).02 . 2. shown in the example below. The thermal absorptivity is calculated as (1.reflectivity . reflectivity and transmissivity [dimensionless] are required (see also Chapter 7). 3. and are fully described in the “Wall” on-line Help topic.0). Thermal radiation properties In thermal radiation problems: 1. you must enter the condition: emissivity = absorptivity = 1 . wall boundary values are needed only for variables pertinent to your problem (see also “Boundary Region Definition” on page 4-5). External walls must be declared as Exposed or Unexposed to incident radiation. The defaults are those for a black body (emissivity equal to 1.transmissivity . reflectivity and transmissivity equal to 0. by selecting the appropriate option from the Solar Heating pop-up 4-20 Version 4. These should be typed in the text boxes provided. Values for thermal emissivity.02 .0.transmissivity).reflectivity Solar radiation properties In solar radiation problems: 1.BOUNDARY AND INITIAL CONDITIONS Wall Boundaries Chapter 4 As with other boundaries. For your wall boundary condition to obey Kirchoff’s law. These are specified via the “Define Boundary Regions” panel for walls. Kirchoff’s law (emissivity = absorptivity) is not enforced by the solver. Thus. However. (b) reflected as diffuse radiation. or (c) transmitted. baffles and solid/fluid interfaces) (b) The external (FASTRAC) DTRM method distinguishes between direct and diffuse solar radiation — see topic Solar Radiation. 4.e.Chapter 4 BOUNDARY AND INITIAL CONDITIONS Wall Boundaries menu. The thermal resistance of an exposed wall to incident solar radiation is neglected. If the FASTRAC method is used. 2. Note that: (a) This option does not apply to internal ‘walls’ (i. 5.g. it is necessary to specify the transmissivity value prior to the view factor calculation. The user input required under the various combinations of thermal and/or solar radiation conditions may be conveniently summarised in the table below: Version 4. 3. Other radiation modelling considerations • • • The FASTRAC method must be used for thermal/solar radiation problems with transmissive external walls. the above option affects both of them equally. Direct radiation transmitted through transparent walls (e. Walls can be made transparent to incident radiation.02 4-21 . is tracked along the angle of solar inclination (specified via the Solar Radiation option in the “Thermal Options” panel) until it falls on an obstructing surface. windows). The remaining user input depends on the problem conditions: (a) If only solar radiation is present: i) The reflected diffuse radiation is neglected ii) The absorptivity is calculated as (1 – transmissivity) (b) If both thermal and solar radiation are present: i) The code treats the two radiation components separately ii) Values of reflectivity and transmissivity for each component are supplied in separate text boxes and the corresponding absorptivity calculated as (1 – reflectivity – transmissivity) iii) Choosing the internal DTRM method for radiation calculations has the effect of making the solar transmissivity equal to the thermal transmissivity. in which case a value of transmissivity [dimensionless] should be supplied in the text box provided. the direct solar radiation received by walls can be (a) absorbed. e. The practice recommended above is particularly important for wall boundaries that strongly influence the character of the flow. e. 3. They are the only valid boundary type for the interfaces between solid and fluid domains. layered structure. Wall function and two-layer models can be used with any kind of mesh.BOUNDARY AND INITIAL CONDITIONS Wall Boundaries . only velocities in directions parallel to the wall surface may be specified. N2-RSTSC. H2O. 6. e. If the mesh is imported from a package that lacks these facilities. For stationary mesh cases. Scalar boundary conditions at solid-fluid interfaces must be set to zero flux. 4. If boundary conditions are set using a table (see page 4-7). 4-22 Version 4.02 . etc. a planar wall can move only within its own plane. for tetrahedral meshes or meshes containing trimmed (polyhedral) cells. N2 etc. Chapter 4 Table 4-1: Summary of radiative surface property requirements Property Condition Emissivity Thermal Thermal & Solar Solar Useful points 1. However.g. Y Y N (=0) N (=0) Reflectivity Y Y Y N (=0) Absorptivity N (=1-R-T) N (=1-R-T) N (=1-R-T) N (=1-T) Transmissivity Y Y Y Y Exposure N Y Y You must also ensure that the coordinate system used is the same as the coordinate system specified in the “Define Boundary Regions” panel. use its built-in mesh generation capabilities. If pro-STAR’s automatic meshing module is employed for this purpose. the permissible variable names that may appear in the table and their meaning is as follows: (a) (b) (c) (d) (e) (f) U — U-component of wall velocity V — V-component of wall velocity W — W-component of wall velocity TORHF — Wall temperature (absolute) or heat flux RESWT — Wall thermal resistance Scalar_name — Mass fraction at the wall. you must extrude the mesh in a direction normal to the boundary so that the wall is located at the edge of the newly-created. For moving mesh cases. all velocity components should in general be specified. Wall boundaries should only be placed on the surfaces of a fluid or solid domain. 2. use the scalar species name.g. as the scalar variable name(s) (g) Scalar_name-RSTSC — Wall resistance for a given species. it is advisable to create at least one cell layer immediately next to the wall boundary (see Figure 4-5 below).g. H2O-RSTSC. 5. They represent solid or porous domains whose physical dimensions are much smaller than the local mesh dimensions. it is necessary to define special boundaries (called baffle boundaries) explicitly on the baffle surfaces. as described in Chapter 2.Chapter 4 BOUNDARY AND INITIAL CONDITIONS Baffle Boundaries Figure 4-5 Example of tetrahedral plus layered mesh structure Baffle Boundaries Introduction Baffles are zero-thickness cells within the flow field. they are assumed to be smooth. stationary. adiabatic walls. as shown in the example of Figure 4-6. as shown in the example below.02 4-23 . Version 4. If no boundary conditions are specified for the baffle surfaces. Figure 4-6 Example model with baffles: duct bend with turning vanes Baffle ‘cells’ are normally defined via the Cell Tool. impermeable. page 2-48 of the Meshing User Guide and should be placed on cell faces inside a fluid domain. If one needs to specify any other conditions. These boundaries can then be grouped into regions and the “Define Boundary Regions” panel can be used to apply the desired conditions. which displays the Side 2 dialog and a message to enter appropriate parameters for that side. ∆ p .BOUNDARY AND INITIAL CONDITIONS Baffle Boundaries Chapter 4 The discussion of porous media in Chapter 6 also applies. 2. including a choice between wall functions and the two-layer model (see the “Baffle” on-line Help topic). the process should be completed by clicking Apply a second time. Side 1 is the ‘outward normal’ side as defined by the cross product of two vectors pointing from the first node to the second node and from the first node to the fourth node. The numbering of the sides is based on the manner in which the baffle was defined. Once this is done. Obviously. The definition of the baffle resistance coefficients is also adjusted to account for this change. it is possible to calculate such a flow by formulating the porous media equation in terms of a pressure drop.02 . Thus. in a modified form. as shown in Figure 4-7. There are a few exceptions which are noted below: 1. It is then necessary to click the Apply button. it is now necessary to provide only one pair of such coefficients. As shown in the example dialog above. 4-24 Version 4. to porous baffles. across the baffle. It is usually possible to impose different boundary conditions on either side of the baffle. conditions for Side 1 are supplied first. Setting up models Inputs for baffle regions are very similar to inputs for walls. 0. An exception to this rule occurs when thermal radiation is switched on. only one set of resistance coefficients is needed.3 3 1 Side 2 2 Side 1 1 Side 2 2 Side 1 Figure 4-7 Numbering convention for various baffle shapes Another way of determining side numbers is to view the baffle cell and consult the cell definition. The absorptivity is calculated as (1 – reflectivity – transmissivity).02 4-25 . The required values are supplied as input for Side 1. in which case radiation properties for both sides of the baffle need to be supplied. The fact that the boundary conditions can be designated separately for each side enables the user to have one side moving and the other stationary or one side isothermal and the other side adiabatic. The defaults are those for a black body (emissivity equal to 1. Values for thermal emissivity. 3. The conditions can be mixed in any combination with two exceptions: (a) If the thermal boundary condition for Side 1 of the baffle is Conduction. Thermal radiation properties In thermal radiation problems: 1. The user should supply values first for Side 1 and then for Side 2 (with the exceptions noted above). 3. STAR-CD calculates the one-dimensional heat transfer across the baffle based on the local temperature and flow conditions on either side. (b) In a similar way. 2. This choice of boundary condition naturally excludes a different choice for Side 2 and therefore the Wall Heat pop-up menu is deactivated for that side.Chapter 4 BOUNDARY AND INITIAL CONDITIONS Baffle Boundaries 4 3. Specific input required for baffles is fully described in the STAR GUIde “Baffle” Help topic. reflectivity Version 4. If the ordering of the cell vertices is counter clockwise. if the baffle is porous. you are viewing Side 1. no input is necessary for Side 2. These should be typed in the text boxes provided. reflectivity and transmissivity [dimensionless] are required (see also Chapter 7). Since these naturally apply to the entire baffle. Therefore.transmissivity . For your baffle boundary condition to obey Kirchoff’s law. absorptivity = 1) (b) The reflected diffuse radiation is neglected (c) As a result. only a reflectivity value needs to be supplied for the solar component. If solar radiation only is present: (a) It is assumed to be completely absorbed by the baffle (i. user input depends on the problem conditions: 1. you must enter the condition: emissivity = absorptivity = 1 .e.BOUNDARY AND INITIAL CONDITIONS Baffle Boundaries Chapter 4 and transmissivity equal to 0. reflectivity and transmissivity [dimensionless] are supplied separately for each radiation component (b) Choosing the internal DTRM method for radiation calculations has the effect of making the solar transmissivity equal to the thermal transmissivity.reflectivity Solar radiation properties In solar radiation problems. no user input is required 2. Table 4-2: Summary of radiative surface property requirements Property Condition Emissivity Thermal Thermal & Solar Solar Y Y N (=0) N (=0) Reflectivity Y Y Y N (=0) Absorptivity N (=1-R-T) N (=1-R-T) N (=1-R-T) N (=1) Transmissivity Y Y Y N (=0) Exposure N N N 4-26 Version 4. Therefore. it is necessary to specify the transmissivity value prior to the view factor calculation. Other radiation modelling considerations • • If the FASTRAC method is used. The effect of baffle transmissivity is taken into account during the view factor calculations. The user input required under the various combinations of thermal and/or solar radiation conditions may be conveniently summarised in the table below: .0). any changes in transmissivity during the run (for example. If both thermal and solar radiation are present: (a) Values for emissivity. Note also that Kirchoff’s law (emissivity = absorptivity) is not enforced by the solver. Note that use of transparent baffles is restricted to surface-to-surface radiation only and thus excludes participating media radiation.02 . as part of a transient calculation) will activate beam tracking and a re-calculation of view factors. The quantities set to zero at the boundary are: • • The normal component of velocity The normal gradient of all other variables Symmetry boundaries should only be placed on the external surfaces of a fluid or solid domain. velocity components are also equalised in a common local coordinate system specified by the user. As shown in Figure 4-8. Cyclic Boundaries Introduction Cyclic boundaries impose a repeating or periodic flow condition on a pair of geometrically identical boundary regions. e. If boundary conditions are set using a table (see page 4-7).02 4-27 . H2O-RSTSC. Selected scalar variables are forced to be equal at corresponding faces on the two regions. This is illustrated by the example of Figure 4-9.g. a planar baffle can move only within its own plane. showing a cascade of repeating baffles. 2. They cannot be used in FASTRAC radiation calculations. N2 etc. etc. numbers 1 and 2 in the example of Figure 4-8. 2. use the scalar species name. e. To approximate a free-stream boundary. No user input is required beyond definition of the boundary location. H2O. the permissible variable names that may appear in the table and their meaning is as follows: (a) (b) (c) (d) (e) (f) U — U-component of baffle velocity V — V-component of baffle velocity W — W-component of baffle velocity TORHF — Baffle temperature (absolute) or heat flux RESWT — Baffle thermal resistance Scalar_name — Mass fraction. Such boundaries thus serve to reduce the size of the computational mesh. For stationary mesh cases. N2-RSTSC. e. For moving mesh cases.g. only velocities in directions parallel to the baffle surface may be specified. Version 4. all velocity components should in general be specified.Chapter 4 BOUNDARY AND INITIAL CONDITIONS Symmetry Plane Boundaries Useful points 1. as the scalar variable name(s) (g) Scalar_name-RSTSC — Baffle resistance for a given species. To reduce the size of the computational mesh by placing the boundary along a plane of geometrical and flow symmetry.g. Symmetry Plane Boundaries Symmetry boundaries are used for two purposes: 1. You must also ensure that the coordinate system used is the same as the coordinate system specified in the “Define Boundary Regions” panel. specify a number of parameters that enable them to be matched to each other geometrically and which take into account the mesh characteristics at either end.BOUNDARY AND INITIAL CONDITIONS Cyclic Boundaries Chapter 4 U2 V1 V2 U1 Cyclic boundary 2 YL U1 = U2 V1 = V2 W1 = W2 ΘL RL Cyclic boundary 1 XL Local cylindrical system Figure 4-8 Cyclic conditions defined using a local coordinate system Cyclic boundary 1 Inlet Cyclic boundary 2 Figure 4-9 Regular cyclic boundaries with integral match Setting up models Cyclic boundaries are defined using STAR GUIde panels in the following multistage process: 1. This involves the following considerations: (a) Specification of suitable coordinate increments (offsets) that allow one 4-28 Version 4.02 . use tab “Regions” to set up a pair of regions. In panel “Create Boundaries”. In tab “Cyclics”. and designate them as cyclic 2. of identical size and shape. as in the examples shown in Figure 4-9 and Figure 4-10. The latter appears in problems where all flow variable profiles have to be reversed in a specified direction of the matching coordinate system. placing the coordinate system origin on an axis of symmetry and choosing its location carefully can eliminate the need for offsets. whereby each cyclic set and the boundaries contributed by each cyclic pair member are named explicitly using command CYCLIC. Cyclic boundary 1 Local Cartesian coordinate system Cyclic boundary 2 Figure 4-10 Partial anticyclic boundaries with integral match (c) Whether there is a one-to-one correspondence between boundary faces on either side of the cyclic pair. In tab “Cyclics”.Chapter 4 BOUNDARY AND INITIAL CONDITIONS Cyclic Boundaries member of the pair to be located if one starts at the other member. A local coordinate system in which the regions are matched is also specified. the system requires an arbitrary matching operation. Thus. as in the anticyclic system shown in Figure 4-10. If no such correspondence exists. “Arbitrary connectivity” in the Meshing User Guide). Version 4. This requires a so-called integral matching operation. Note that the same operation may also be performed manually. The latter is similar to matching cell faces on either side of an interface between mesh blocks (see Chapter 3. (b) Whether the regions form a regular cyclic (as in Figure 4-9) or an anticyclic pair (as in Figure 4-10). This operation also reverses the coordinate value of each boundary face in that direction before adding the corresponding offset. beginning from a pre-existing starting set. 3. typically because one side is more finely meshed than the other (as in Figure 4-11). It thus involves matching of so-called master boundary faces on one side of the cyclic pair with slave faces on the other side. The list of cyclic pairs can also be extended with the CYGENERATE command.02 4-29 . finish up by performing the geometric matching operation between boundary faces on either side of the pair to form so-called cyclic sets. the bulk mean temperature on the inflow side of the cyclic pair is also required. whereby the matching process is subject to an additional constraint of either a prescribed pressure drop or a fixed mass flow rate across the cyclic pair. as shown below: These can be of two types: (a) Ordinary cyclic conditions. whereby all flow variable values on one member are matched with the corresponding values on the other member.BOUNDARY AND INITIAL CONDITIONS Cyclic Boundaries Chapter 4 Figure 4-11 Cyclic boundaries with arbitrary match 4. specify the physical cyclic boundary conditions that exist between the members of the pair. One member of the cyclic pair must be designated as an Inflow boundary and the other as an Outflow boundary 4-30 Version 4. In panel “Define Boundary Regions”. An example of a fixed mass flow rate system. is shown in Figure 4-10. For thermal problems. (b) Partial cyclic conditions.02 . Useful points 1. representing one half of a continuous loop flow system. The sets are numbered and listed in numerically ascending order. together with their constituent master and slave boundary numbers for arbitrarily matched regions (see page 4-29 above). Partial cyclic conditions can only be applied to boundaries matched in Cartesian coordinates 5. the inflow and outflow sides are distinguished by assigning a pressure drop or flow rate to one member that is equal in magnitude but of opposite sign to that for the other member. If the partial cyclic condition is specified via the STAR GUIde interface. The sign convention is as follows: (a) Pressure Drop + Inflow – Outflow (b) Flow rate + Outflow – Inflow 4. 8.Chapter 4 BOUNDARY AND INITIAL CONDITIONS Cyclic Boundaries 2. Cyclic set manipulation All currently defined cyclic sets are shown in the Cyclic Set List below: Commands: CYLIST CYDELETE CYCOMPRESS The list may be displayed by choosing Lists > Cyclic Sets from the main menu bar. Note that this number must be the same for both members of the pair. Arbitrary cyclic matching (see page 4-29 above) is not allowed for partial cyclic conditions 7. Such conditions are not available for chemical species mass fractions and cannot be used in variable-density flows 6. the Inflow and Outflow sides are indicated via the Flow Direction menu and the pressure drop or flow rate must be a positive number. Cyclic boundaries cannot be used in FASTRAC radiation calculations. 3. There is a choice of showing all cyclic sets (click button Show All Cyclic Sets) or just those with at least one member (master or slave boundary) in the current boundary set (click button Show Cyclic Sets with Boundaries in Version 4. Cyclic boundaries should only be placed on the external surfaces of a fluid domain.02 4-31 . If the partial cyclic condition is specified via the RDEFINE command. 4-32 Version 4. the following operations are possible: • • Deletion — click on the Delete button. the overlapping areas from either side match up.BOUNDARY AND INITIAL CONDITIONS Free-stream Transmissive Boundaries Chapter 4 Bset Only). Items in the second category are marked by asterisks in the Bset column. Decide on an appropriate location for the boundary. you need to: 1. In the case of turbulent inflow (expansion waves). To select cyclic sets from the list: • • For single items. click the first set you want to select. click the required set number.02 . 2. without reflection. press and hold down the Shift key and then click the last set in the group. Flow can be out of the solution domain (compression waves) or into the solution domain (expansion waves). is implemented in the “Check Everything” panel. The operation checks that • • • all sets in a given range exist and reference arbitrarily-matched cyclic regions. For two or more items in sequence. To set up boundaries of this kind. A third operation. there is overlap between boundaries on the two sides of the cyclic set. the turbulence quantities have to be specified as part of the user input. Once the desired sets are selected. Compression — click on the Compress button. This involves the elimination of all deleted cyclic sets and renumbering of the remaining ones. All checks are performed to within a specified tolerance. as shown in the example below. preferably parallel to the main (supersonic) stream. The facility enables shock waves generated in the interior of the solution domain to be transmitted. through the boundary to the wider (free stream) space surrounding the domain. Free-stream Transmissive Boundaries Introduction This type of boundary may be used only in models involving supersonic free streams where the working fluid is an ideal gas. The required input is fully described in the “Free-stream Transmissive Boundary” on-line Help topic. Supply values in the “Define Boundary Regions” panel for all free-stream properties. for validating arbitrarily matched cyclic boundaries. In either case. boundary values of scalar variables are extrapolated from the solution domain interior. 4.Chapter 4 BOUNDARY AND INITIAL CONDITIONS Free-stream Transmissive Boundaries The STAR-CD solver calculates the magnitude and direction of the flow at the boundary as part of the analysis. Useful points 1. i. If this is not the case. you must extrude the mesh in a direction normal to the boundary and then shift the boundary location to the edge of the newly-created.02 4-33 . Boundary values for turbulence in domains using a Reynolds Stress model may be specified solely in terms of k and ε instead of Reynolds Stress components. Boundary conditions specified in a table will be applied only if fluid is entering the solution domain from the outside. before defining the boundary conditions. layered structure. 3. A value of temperature at the boundary is obligatory. boundary values will be extrapolated from interior values and the table data will not be used. If pro-STAR’s automatic meshing module is employed for this purpose. The user must therefore ensure that temperature calculations are activated. 2. If boundary conditions are set using a table (see page 4-7).the flow is parallel to the boundary or crossing it from inside the domain.e. If the mesh is imported from a package that lacks these facilities. it is necessary to create at least two cell layers immediately next to the boundary (see Figure 4-5 on page 4-23). turbulence conditions at the boundary are assumed to be isotropic. use its built-in mesh generation capabilities. 5. the permissible Version 4. via the “Thermal Models” panel. To obtain a stable/convergent solution for tetrahedral meshes or meshes containing trimmed (polyhedral) cells. If this option is chosen. based on the simple wave theory given in [3] and [4]. Decide on an appropriate location for the boundary 2. STAR-CD uses the simple wave theory to calculate conditions behind the wave and to specify such conditions at the boundaries. Transient-wave Transmissive Boundaries Introduction This type of boundary may be used only in transient. Switch setting (g) EDINF — Turbulent kinetic energy dissipation rate or length scale. It enables transient waves to leave the solution domain without reflection. depending on the Turb. 4-34 Version 4. you need to: 1. depending on the Turb. 6. Switch setting You must also ensure that the coordinate system used is the same as the coordinate system specified in the “Define Boundary Regions” panel. The required input is fully described in the “Transient-wave Transmissive Boundary” on-line Help topic. Free-stream transmissive boundaries should only be placed on the external surfaces of a fluid domain. To set up boundaries of this kind.02 . compressible flows where the working fluid is an ideal gas. Supply values in the “Define Boundary Regions” panel for all dependent variables.BOUNDARY AND INITIAL CONDITIONS Transient-wave Transmissive Boundaries Chapter 4 variable names that may appear in the table and their meaning is as follows: (a) (b) (c) (d) (e) (f) UINF — U-component of velocity VINF — V-component of velocity WINF — W-component of velocity PINF — Pressure (relative) TINF — Temperature (absolute) TEINF — Turbulent kinetic energy or intensity. representing conditions outside the boundary (at ‘infinity’). boundary values will be extrapolated from interior values and the table data will not be used. use its built-in mesh generation capabilities. 2. before defining the boundary conditions. If this option is chosen.Chapter 4 BOUNDARY AND INITIAL CONDITIONS Transient-wave Transmissive Boundaries STAR-CD calculates the magnitude and direction of the flow at the boundary as part of the analysis. If pro-STAR’s automatic meshing module is employed for this purpose. Boundary conditions specified in a table will be applied only if fluid is entering the solution domain from the outside. i. it is necessary to create at least two cell layers immediately next to the boundary (see Figure 4-5 on page 4-23). Useful points 1. A value of temperature at the boundary is obligatory. the permissible Version 4. layered structure. The user must therefore ensure that temperature calculations are activated. via the “Thermal Models” panel. you must extrude the mesh in a direction normal to the boundary and then shift the boundary location to the edge of the newly-created. 3. To obtain a stable/convergent solution for tetrahedral meshes or meshes containing trimmed (polyhedral) cells. If boundary conditions are set using a table (see page 4-7).02 4-35 . Boundary values for turbulence in domains using a Reynolds Stress model may be specified solely in terms of k and ε instead of Reynolds Stress components. If the mesh is imported from a package that lacks these facilities.the flow is parallel to the boundary or crossing it from inside the domain. 5.e. 4. If this is not the case. based on the transient wave theory given in [3] and [4]. turbulence conditions at the boundary are assumed to be isotropic. you need to: 1. depending on the above setting You must also ensure that the coordinate system used is the same as the coordinate system specified in the “Define Boundary Regions” panel. 6. It enables weak pressure waves to leave the solution domain without reflection and is valid for both steady-state and transient problems. Switch setting (g) EDINF — Turbulent kinetic energy dissipation rate or length scale. To set up boundaries of this kind. Decide on an appropriate location for the boundary 2. depending on the Turb.BOUNDARY AND INITIAL CONDITIONS Riemann Boundaries Chapter 4 variable names that may appear in the table and their meaning is as follows: (a) (b) (c) (d) (e) (f) UINF — U-component of velocity VINF — V-component of velocity WINF — W-component of velocity PINF — Pressure (relative) TINF — Temperature (absolute) TEINF — Turbulent kinetic energy or intensity. representing conditions outside the boundary (at ‘infinity’).02 . The required input is fully described in the “Riemann Boundary” Help topic. Transient-wave transmissive boundaries should only be placed on the external surfaces of a fluid domain. Supply values in the “Define Boundary Regions” panel for all dependent variables. Riemann Boundaries Introduction This type of boundary is typically employed in external aerodynamics simulations and may be used only if the working fluid is an ideal gas. 4-36 Version 4. layered structure. turbulence conditions at the boundary are assumed to be isotropic. it is necessary to create at least two cell layers immediately next to the boundary (see Figure 4-5 on page 4-23). Boundary values for turbulence in domains using a Reynolds Stress model may be specified solely in terms of k and ε instead of Reynolds Stress components. Useful points 1. 3. boundary values will be extrapolated from interior values and the table data Version 4. i. The user must therefore ensure that temperature calculations are activated. To obtain a stable/convergent solution for tetrahedral meshes or meshes containing trimmed (polyhedral) cells. If this is not the case. Boundary conditions specified in a table will be applied only if fluid is entering the solution domain from the outside. If pro-STAR’s automatic meshing module is employed for this purpose. use its built-in mesh generation capabilities.the flow is parallel to the boundary or crossing it from inside the domain. 4. If the mesh is imported from a package that lacks these facilities.e. you must extrude the mesh in a direction normal to the boundary and then shift the boundary location to the edge of the newly-created. A value of temperature at the boundary is obligatory. via the “Thermal Models” panel. Check that the density of the domain to which such a boundary belongs is set to Ideal-f(T. based on the Riemann invariant theory given in [7]. If this option is chosen.P) 2.Chapter 4 BOUNDARY AND INITIAL CONDITIONS Riemann Boundaries STAR-CD calculates the magnitude and direction of the flow at the boundary as part of the analysis. before defining the boundary conditions. 5.02 4-37 . “Cell Attachment and Change of Fluid Type”). To define the interface between cells that may be connected or disconnected from each other (see Chapter 12. use the scalar species name. H2O. To define the interface between mesh blocks that slide past each other. The alternate boundary region 4-38 Version 4.g. as the scalar variable name(s) You must also ensure that the coordinate system used is the same as the coordinate system specified in the “Define Boundary Regions” panel. either in an ‘integral’ or ‘arbitrary’ manner — see “Regular sliding interfaces” on page 12-18. 2. If boundary conditions are set using a table (see page 4-7). depending on the Turb. Switch setting (g) EDINF — Turbulent kinetic energy dissipation rate or length scale. Attachment Boundaries Attachment boundaries are used for the following two purposes: 1. 6. Two input parameters are needed: • • A local coordinate system in which the boundaries are to be matched An alternate boundary region number The second parameter is required for cell layer attachment cases and serves to maintain appropriate boundary conditions in the solution domain if the cells on either side of the interface become disconnected.02 . the permissible variable names that may appear in the table and their meaning is as follows: (a) (b) (c) (d) (e) (f) UINF — U-component of velocity VINF — V-component of velocity WINF — W-component of velocity PINF — Pressure (relative) TINF — Temperature (absolute) TEINF — Turbulent kinetic energy or intensity. e. depending on the above setting (h) Scalar_name — Mass fraction. N2 etc. Riemann boundaries should only be placed on the external surfaces of a fluid domain. 7.BOUNDARY AND INITIAL CONDITIONS Attachment Boundaries Chapter 4 will not be used. normally set to a value close to the expected temperature in the surrounding area 2. the boundary must be placed on the cells that are inside the 4-39 • • Version 4. one on each of the mesh blocks that are attached to. Its presence does not adversely affect the accuracy of the calculations inside the radiative sub-domain(s) If a coupled-cell interface exists between the radiative and non-radiative sub-domains.02 . The boundary surface emissivity [dimensionless]. Examples of cases requiring attachment boundaries are given in Chapter 12. Useful points 1. Two input parameters are needed (see also Chapter 7): 1. Radiation Boundaries Radiation boundaries are used for the purpose of separating that part of your model where radiation effects are important from other parts where such effects are negligible. This type of boundary only influences radiation calculations and is completely transparent to the fluid flow and non-radiative heat transfer in your model. Attachment boundaries should be placed on the surfaces of domains/ subdomains.Chapter 4 BOUNDARY AND INITIAL CONDITIONS Radiation Boundaries must be of ‘wall’ or ‘inlet’ type. it is necessary to create at least two cell layers immediately next to the boundary (see Figure 4-5 on page 4-23). 2. you must extrude the mesh in a direction normal to the boundary and then shift the boundary location to the edge of the newly-created. detached from or sliding past each other. Attachment boundary regions must be created in pairs. normally set to 1. layered structure.0 The location and properties of such a boundary should be chosen so that: • Radiant energy passing through it escapes to the outside world with minimal back-radiation into the sub-domain where it emanated. 3. To obtain a stable/convergent solution for meshes containing trimmed (polyhedral) cells. If the mesh is imported from a package that lacks such facilities. The boundary radiation temperature [K]. use its built-in mesh generation capabilities for this purpose. The escaped radiation should be low enough not to influence conditions in the outside world. If the pro-STAR Auto Mesh module is employed. allowing the liquid to flow parallel to the boundary surface without friction 2. The boundary conditions applied to each phase are as follows: 1. such that the mass flux is defined as being positive when it leaves this cell through the face. so it will be zero in solid materials Each face of a monitoring region “belongs” to a neighbouring cell. Useful points 1. For the continuous phase. except that: • • • Item Heat Flux is not available Field values are taken from the neighbouring cell centres and are not interpolated to the boundary Item Enthalpy In/Out is based on convection only. the boundary acts like an opening allowing bubbles to escape into the surrounding medium. The same data values are available at monitoring regions as at open boundary regions. Note that only one boundary of this type should be present in your model. For the dispersed phase. defined in the same way as ordinary boundaries but placed on any cell faces within a fluid or solid domain so as to form internal surfaces. corresponding to the dispersed and continuous phases. 3. No further user input is required on the “Define Boundary Regions” panel. They are used purely for monitoring engineering data such as mass flux (see panel “Monitor Boundary Behaviour”) so no further user input is required on the “Define Boundary Regions” panel. Monitoring regions do not affect the flow field in any way. STAR simply calculates the monitored data values at the specified region’s surface and stores them for subsequent display as a function of time or number of iterations (see panel “Engineering Data”). 2. Degassing boundaries should only be placed on the external surfaces of a fluid domain. for consistent calculation of the total 4-40 Version 4. The use of radiation boundaries is not required in radiation problems employing the Discrete Ordinates method.02 . Phase-Escape (Degassing) Boundaries This type of boundary appears exclusively in Eulerian multi-phase problems (see Chapter 10 of this volume) and represents a degassing free-surface bounding a two-phase system of gas bubbles in a liquid. Radiation boundaries should be placed on cell faces inside a fluid domain. respectively. the boundary acts like a slip wall. Monitoring Regions These are arbitrary surfaces. unless retained within the solution domain by the drag forces acting on them.BOUNDARY AND INITIAL CONDITIONS Phase-Escape (Degassing) Boundaries Chapter 4 radiative sub-domain. Turning radiation off for a particular cell type is sufficient to exclude radiation calculations in that mesh region. Radiation boundaries are currently incompatible with FASTRAC radiation calculations. This in turn determines the face’s orientation and. The choice of which cell a monitoring region face belongs to is made when that face is defined.02 4-41 . as do their associated GUI operations.Chapter 4 BOUNDARY AND INITIAL CONDITIONS Boundary Visualisation mass flux through the region. commands BDEF. characteristic of the boundary type represented. and are therefore suitable for this purpose. Alternatively. Note that the boundary display option may also be selected by choosing Plot > Cell Display > Boundaries from the menu bar. it is important that all its faces are oriented the same way. BCROSS. their orientation is indicated using an arrow normal to the boundary and whose direction indicates the direction of positive flux. BREGION in the I/O window. Boundary faces will be superimposed on any kind of plot already displayed on the screen other than a section plot. Figure 4-12 Monitoring region display Boundary Visualisation As described in “Boundary set selection facilities” on page 4-3. Version 4. The currently defined set can then be displayed on top of the calculation mesh by choosing Cell Plot Display Option Bound from the main window and re-plotting. When visualising monitoring regions. boundaries can be collected into sets. Commands BFIND. Caution should also be exercised when generating such regions automatically. for example by cell refinement. ON or CDISPLAY. BGEN and BDX should not be used to define monitoring region faces as they do not involve the explicit selection of a cell face and hence the orientation of the monitoring region face is indeterminate. as shown in Figure 4-12 below. The cell faces representing the boundaries will be marked by distinctive fill patterns and colours. you may type commands BDISPLAY. On the other hand. and BZONE do this by picking a cell face. Specify uniform values — select option Constant in the “Initialisation” panel 4-42 Version 4. the turbulence kinetic energy k and dissipation rate ε are computed as follows: k = 1.5 U I k ε = ------l 1. this can be done in one of the following ways: 1. • For chemically reacting flows. Restart runs Various options for this operation are available in panel “Analysis (Re)Start” within the Analysis Preparation/Running folder. If this is done by specifying the initial turbulence intensity I and length scale l. you may also need to use panel “Initialisation” in the Additional Scalars sub-folder to specify initial mass fractions for chemical species. another panel also called “Initialisation” in the Solids sub-folder can be used to specify initial temperatures in solid materials. the solution from a previous run serves as the starting point for the current run. Initial runs Initial conditions for flow field variables are assigned in STAR-GUIde’s Thermophysical Models and Properties folder: • For fluid field variables. all flow field variables should be given the correct values for the problem at hand. Depending on the physical conditions being modelled.02 . If option Standard Restart is chosen. the STAR-CD solver only corrects the mass fluxes to satisfy continuity. “Solution Control with Mesh Changes”. the turbulence scales (ω for k-ω models or ν t for the Spalart-Allmaras model) are computed automatically. • In conjugate heat transfer problems. typically a refinement of a coarser starting mesh. use panel “Initialisation” in the Liquids and Gases sub-folder. If Initial Field Restart is chosen in this panel. For turbulence models other than the k-ε type. The Initial Field Restart option should be chosen if any change has been made to the boundary conditions or reference quantities (pressure and/or temperature). These are covered in Chapter 5.BOUNDARY AND INITIAL CONDITIONS Solution Domain Initialisation Chapter 4 Solution Domain Initialisation Steady-state problems User action depends on whether the solution is to start from the initial state of the model (initial run) or to continue from a previously computed solution (restart run). This option must also be chosen if new scalars have been defined by selecting additional modelling options such as Lagrangian multi-phase or chemical reaction.5 2 2 (4-2) (4-3) where U is the initial velocity magnitude. Transient problems In transient problems. Special considerations apply to cases where the restart also involves a change in the mesh configuration. Note that there is a separate “Turbulence tab” for initializing turbulence parameters. Read in a previously computed distribution that corresponds to the desired setting — select an option from the “Analysis (Re)Start” panel (usually Initial Field Restart plus one of the options in the Initial Field Restart pop-up menu depending on the problem at hand).02 4-43 .Chapter 4 BOUNDARY AND INITIAL CONDITIONS Solution Domain Initialisation and then type values for each variable in the text boxes provided. Version 4. 2. as the meaning of the droplet treatment is different between steady-state and transient analyses. Option Standard Restart must be used for all moving mesh cases and should also be chosen to start a transient analysis from a previously computed steady-state solution. Set values through a user-supplied subroutine — select option User in the Initialization panel and then specify the required distributions in subroutine INITFI. Turbulence parameters. scalar mass fractions and solid temperatures may be initialised as described in section “Initial runs” above for steady-state cases. Note that such restarts should not be performed for Lagrangian multi-phase cases. 3. . and the pseudo-transient mode is usually better suited to this class of problems. In such cases. the following tasks should have been completed: 1. Material property and continuum mechanics model specification 3. Mesh set up 2. Note. in the former. An iterative method employing under. Introduction The user should also decide whether the problem is steady-state or transient so as to perform the appropriate operations for the above tasks. so it is important to have a basic understanding of their significance and effect during a run. however. pressure waves in compressible fluids. it is important that waves travel in all cells with the same pseudo time step. non-reacting and low Mach number flows usually converge smoothly and fast in a combination with the inertial under-relaxation shown in equation (7-14) of the Methodology volume. inviscid flows and where the initial velocity field is zero). For this. A pseudo-transient time marching to the steady-state solution with a fixed-length time step. the under-relaxation Version 4. or gravity waves in free surface flows) can reach a steady state. the convergence process is typically much more robust and stable if one can resolve to some extent the waves travelling during the iteration process.2) is still used on the pressure correction equation.02 5-1 . In flows which exhibit this kind of problem.g. we can have very small or zero values of the central coefficients A P at an early stage of the iteration process. In other problems (e.Chapter 5 CONTROL FUNCTIONS Introduction Chapter 5 CONTROL FUNCTIONS At this stage of modelling. You are therefore advised to refer to Chapter 7 in the Methodology volume for a detailed discussion of under-relaxation and other solution control topics.relaxation factors 2. local pseudo time steps become very large or infinite (see equation (7-19)). STAR-CD offers two alternatives for solving steady-state problems: 1. that an under-relaxation factor (default value 0. Incompressible. This consists of • • setting various parameters that affect the progress of the numerical solution algorithm used by STAR. The main advantage of the iterative method employing under-relaxation factors compared with the pseudo-transient mode is that. specifying the type and amount of run-time output and post-processing data. which again has an impact on the convergence and stability of the solution.g. use of the pseudo-transient mode is recommended. Definition of boundary type and location The penultimate task before a STAR analysis run is to set the parameters that control that run. Analysis Controls for Steady-State Problems Solution controls Solution control parameters have a strong influence on the progress of the analysis. If fluid flows which are characterized by travelling waves (e. maximum acceptable level of remaining error in the solution) should be specified. specify the maximum residual error tolerance (i. as in ordinary steady-state runs. the normalised residuals are displayed on the screen and also saved on file case.2 for pressure correction) that are based on considerable past experience.CONTROL FUNCTIONS Analysis Controls for Steady-State Problems Chapter 5 factors vary between 0 and 1 and a large number of cases run nearly optimally with default values (e. lower values of time step are more likely to promote convergence. the time step varies between zero and infinity and a suitable value is not always easy to find.e.e. number of calculation sweeps and residual error tolerances for each solution variable). maximum acceptable level of remaining error in the solution). Step 4 Check the “Solver Parameters” (under-relaxation factors. inspect the solution status for flow variables and material properties (see topic “Equation Status”) to confirm that the right variables will be solved for. • Pseudo-Transient for pseudo-transient runs (see topic “Pseudo-Transient Solution”). The optimum value can be determined only by numerical experiments.g. As a guideline.02 • . in the pseudo transient approach. Output controls can be applied by going to the Output Controls folder in the STAR GUIde system and following the steps 5-2 Version 4. Also choose the numerical algorithm to be used (see topic “Steady-State Solution”).7 for momentum and 0. plus any additional parameters required by the algorithm you have chosen. The maximum residual error tolerance (i. It is suggested that higher-order differencing schemes such as LUD or MARS should be used if high spatial discretisation accuracy is required. the next task is to choose the type and volume of output from the forthcoming STAR run. However. one should choose a time step such that the Courant number based on the characteristic velocity and the characteristic mesh size is between 1 and 8. Step 3 In the “Primary Variables” panel. while larger ones lead to a faster solution. Output controls Having set the solution control parameters. 0. Step 5 Choose one of the available “Differencing Schemes”. In every case. The task of setting up solution controls for either of these methods can be divided into the following steps: Step 1 Start up the STAR GUIde system and then define the type of problem you are solving by selecting Steady State from the Time Domain pop-up menu in the “Select Analysis Features” panel Step 2 Go to the Solution Controls folder and open the “Solution Method” panel. Note that. From the pop-up menu at the top of the panel select: Steady State for conventional steady-state runs. as with under-relaxation.run. The bulk of this output consists of solution variable values at cell centroids. respectively). If desired. according to the type of problem being analysed.e. You can also select what wall data are to be ‘printed’ (i. accessible from the Utilities menu in the main window (or issue command EDATA). from where they may be displayed as pro-STAR graphs at the end of the analysis (see panel “Engineering Data” in the Post-Processing folder) or read by an external post-processing package. and the type of monitoring information to be generated for them The requested data are stored in special files (case. defined in terms of cell sets. Step 10 Go to the Analysis Preparation/Running folder and open the “Set Run Time Controls” panel: • Version 4.Chapter 5 CONTROL FUNCTIONS Analysis Controls for Steady-State Problems below: Step 6 Consider whether detailed printout on the solution progress is required and if necessary specify the appropriate settings in the “Monitor Numeric Behaviour” panel. An alternative way of performing this function is to enter special debugging instructions into the Extended Data panel. it is up to you to check the default settings and change them. if necessary. go to the “Additional Output Data” section to select any wall data to be included in the solution (. go to the Monitor Engineering Behaviour sub-folder and use one or both of the following panels: • • “Monitor Boundary Behaviour” — select one or more boundary regions and the type of monitoring information to be generated for them “Monitor Cell Behaviour” — select one or more sub-domains. displayed on your screen) and stored in the .02 For conventional steady-state runs. This is important. enter the maximum number of iterations 5-3 .ccm) file. Step 8 Specify the manner of saving mesh data for use in post-processing and/or restart runs via the “Analysis Output” panel (“Steady state problems”).erd and case.run file at the end of the run. Note that STAR-CD provides special switches and constants for activating various beta-level features in the code. as these settings will affect the availability of data for post-processing. Step 7 Decide whether you want to follow the progress of the analysis by generating various types of monitoring data at every iteration. For both post and print control parameters. Other controls Step 9 Go to the Sources sub-folder and inspect the “Source Terms” panel to see if any additional information (such as extra source terms for flow variables) is needed to completely describe your problem.ecd for boundary and cell data. or for turning on calculation procedures designed for debugging purposes. If so. These are found in the “Switches and Real Constants” panel and are normally used only after consultation with CD-adapco. thermal and chemical fields are originally in thermodynamic equilibrium and which are subjected to a set of non-equilibrium boundary conditions at the start of the calculation. e. as in some buoyancy driven flows. hence the name ‘single transient’. Systems whose flow. Inherently unstable systems that never reach a steady state and exhibit either (a) a cyclic (or periodic) behaviour. as in some vortex shedding problems.02 .g. Systems whose boundary conditions change in a prescribed fashion. The system’s response is to gradually approach a new steady state. is the quickest and easiest way of setting up transient problems. chemical species and density equations. due to opening and shutting of flow valves. “Buoyancy-driven Flows and Natural Convection”). A variable step magnitude may also be specified via user subroutine DTSTEP. 2. “Table Manipulation”) Changes in boundary region type (e. Other important characteristics are: • • • It is fully supported by pro-STAR’s STAR GUIde interface It can accommodate problems with time-varying boundary conditions through the use of tables (see Chapter 2. some buoyancy driven flows are best run in transient mode (see also Chapter 3. by selecting option User in the Time Step Option pop-up menu (see “Steady state problems (Pseudo-transient)”). 3. Set the appropriate solution controls in the “Analysis (Re)Start” panel. Step 11 To complete the controls specification. by eliminating the need for a transient history file and explicit load step definitions. Analysis Controls for Transient Problems Transient problems can be divided into three groups: 1.CONTROL FUNCTIONS Analysis Controls for Transient Problems Chapter 5 (or calculation loops. referred to as the ‘single-transient’ solution mode in earlier versions of STAR-CD. Default (single-transient) solution mode This procedure. you need to decide whether the analysis is to start from initial conditions or restart from a previous run. Procedures for solving all of these problem types are described below. 5-4 Version 4. specify the time step size and the maximum number of time steps. It is in fact equivalent to performing a single load step. Such problems can be analysed in STAR either in the steady-state or transient mode. It is also suitable for steady-state compressible or buoyancy driven flows that require close coupling between the momentum. see “Steady state problems”). enthalpy.g. a pressure boundary changing to a wall boundary) are also possible but require stopping and restarting the analysis at those times when such changes occur The single-transient mode provides an alternative to the “Load-step based solution mode” discussed below. or (b) chaotic behaviour. • For pseudo-transient runs. follow the procedure below. To use this approach. pstt. These are defined by the parameters entered in the “Transient tab”.run file at the end of the run. contains user-selected data. 2. written at predetermined points in time. consult Chapter 1. etc. specify control parameters for the wall data that will be written to the solution (. (b) The data display appearing on your screen at predetermined points in time (not necessarily the same as the ones specified for the post data). Step 3 Display the “Primary Variables” panel and check that the solution parameter settings are appropriate for your case. Select the numerical algorithm to be used (see topic “Transient problems”). If there is any need for alterations. On the other hand. such as cell pressures.02 5-5 . Step 2 Go to the Solution Controls folder and open the “Solution Method” panel.ccm) file is as follows: i) File case. In the “Post tab”. However. Also select the time differencing scheme required.pstt) file. wall heat fluxes.ccm contains analysis results only for the last time step. The file is therefore suitable for post-processing runs but cannot be used to restart the analysis. Output controls The output to be produced by a transient run is chosen in a similar manner to that for steady-state problems. If the analysis is split into several stages. on the other hand. “Transient flow calculations with PISO” or “Transient flow calculations with SIMPLE” in this volume for information and advice.run) file.ccm) file and/or printed and saved in the . The “Transient tab” control parameters must be used with care since they could cause excessively large data files to be written. ii) File case. in the same manner as for steady-state problems. In the “Transient tab”. This information is also saved in the run history (. since the volume of data that can be generated is potentially very large.Chapter 5 CONTROL FUNCTIONS Analysis Controls for Transient Problems Solution controls Step 1 Start up the STAR GUIde system and then define the type of problem you are solving by selecting Transient from the Time Domain pop-up menu in the “Select Analysis Features” panel. additional controls are provided to limit the amount to what is absolutely essential. they must not be used too sparingly as they may fail to record important data. 1. These form a complete set of all cell data relevant to the current problem and the file can therefore be used to restart the analysis. specify control parameters for data destined for: (a) The transient post data (. The difference between this and the usual solution (. Step 4 Open the “Analysis Output” panel (“Transient problems”). as is usually the case with large models and/or lengthy Version 4. called load steps in pro-STAR terminology. Set the appropriate solution controls in the “Analysis (Re)Start” panel.02 • 5-6 . whether you want to generate monitoring data at every time step. The method of calculating the time step size and the total number of time steps. it is more complex to set up and maintain as it requires definition of so-called ‘load steps’ (see “Load step characteristics” below) and their storage in special transient history files. the main considerations are: • To define the variation in boundary conditions as a series of events which occur over a period of time. Load-step based solution mode This older procedure allows for all intricacies in the transient problem specification.CONTROL FUNCTIONS Analysis Controls for Transient Problems Chapter 5 transients. Version 4.20 or later. e. in the same manner as for steady-state problems. To divide each load step into several time increments. represent a transition from one state of the boundary conditions to another with increasing time. “Moving Meshes”) It does not support models containing features introduced in STAR-CD V3.g. it is advisable to give the . Step 7). Step 7 Go to the “Set Run Time Controls” panel (Analysis Preparation folder) and specify: 1. such as Eulerian multi-phase and liquid films Load step characteristics For problems involving changing boundary conditions. Step 5 Specify any other output controls required. in the same manner as for steady-state problems (see “Analysis Controls for Steady-State Problems”. see “Transient problems” Step 8 To complete the controls specification. This helps to spread the output produced amongst several files and thus eases the data management and manipulation processes. you need to decide whether the analysis is to start from initial conditions or restart from a previous run.pstt file produced at the end of each stage a unique file name. These events. as described in the sections to follow. accessed by selecting Modules > Transient in pro-STAR’s main menu bar Time variations may be specified only in terms of load steps. including variable boundary conditions. Other important characteristics are: • • • • It is driven by its own special user interface. the Advanced Transients dialog. Other controls Step 6 Specify any other necessary controls in the Sources and Other Controls sub-folders. the use of tables is not permissible It is part of the recommended procedure for setting up moving-mesh cases defined via pro-STAR ‘events’ (see Chapter 12. However. or time steps. The analysis run time 2. 3. as shown in Figure 5-2. the value at the start and at all intermediate times is kept equal to value at the end time. see Figure 5-1(a). as specified in stage 2. Ramp — where the values change linearly between the state at the beginning of the load step to that at the end. the value at the start is made equal to that specified at the previous load step. 2. above. 3. as shown in Figure 5-1(c)–(d). Step — where the boundary values change discontinuously from one state to the next. The action of the program is then as follows: (a) For step settings. see Figure 5-1(b).02 5-7 . The following information is specified every time a load step is defined: 1. All intermediate values vary linearly between the start and end values. Any combination of load step types can be specified. The manner in which the boundary values should vary between the start and end of the load step. Version 4.Chapter 5 CONTROL FUNCTIONS Analysis Controls for Transient Problems The allowable variations in the boundary conditions are as follows: 1. The boundary values prevailing at the end of the load step. The number of time steps to be performed. Function of time — where the variation is arbitrary and is prescribed via a user subroutine. Boundary condition value Boundary condition value S 1 S 2 (a) S 3 S 4 Time R 1 R 2 R 3 R 4 (b) R 5 Time Boundary condition value Boundary condition value S 1 S 2 R 3 (c) R 4 R 5 Time R 1 R 2 R 3 R 4 (d) S 5 S 6 Time Figure 5-1 Representation of boundary value changes by load steps The difference between the available alternatives is illustrated in Figure 5-2 for load step number n and a time increment of DT. 2. (b) For ramp settings. 02 . Boundary condition value Load step n–1 A Load step n User coding Ramp B Step Load step n+1 DT Time Figure 5-2 Types of change in boundary conditions Some examples of different load step sequences are shown in Figure 5-1 where the letters S and R denote a step or ramp setting respectively. 3. new boundary regions cannot be added or existing ones deleted. dummy load step which merely serves to supply the required boundary value. The size should be small enough to meet the following two 5-8 Version 4. When the boundary values at the start and end of a load step are identical. 4. The problem is resolved by defining an extra. 2. Examples of this situation are shown in Figure 5-1. For example. A step setting is always imposed at every boundary type change. boundaries that were previously outlets can now become walls and vice versa. However. The time step size can vary from one load step to the next to suit the problem conditions. cases (b) and (d). nor can the physical extent of the boundaries be modified in any way. Special considerations apply if the very first load step has a ramp setting. At each new load step. The user must therefore plan the model’s boundary region definitions adequately before starting a transient analysis. values between the start and end times vary in an arbitrary manner. according to what is prescribed in the user-supplied subroutine (see Figure 5-2). Load step definition The user should bear in mind the following points when defining load steps: 1.CONTROL FUNCTIONS Analysis Controls for Transient Problems Chapter 5 (c) For user settings. the user is free to modify any existing boundary region definition. This is because there is no previous load step to fix the value of its starting point. the sole purpose of defining the load step would be to permit subdivision of time into discrete time steps so as to track the transient behaviour of the flow field. by minimising the cumulative error in the numerical solution.Chapter 5 CONTROL FUNCTIONS Analysis Controls for Transient Problems targets: (a) Stability of the numerical solution algorithm. The time step should be chosen such that the maximum Courant number does not exceed 100. For optimum results.g. Although precise figures cannot be given for all cases. Therefore. by setting v to the estimated average velocity in the flow field and l to a characteristic overall dimension of the model (e. a Courant number derived from this criterion is typically in the range 100 to 500. Cell-wise. a dimensionless quantity given by v ∆t Co = ----------l (5-1) where v and l are a characteristic velocity and dimension. respectively. where c is the velocity of sound. (b) Capture of the transient details of the flow.02 5-9 . Note that in compressible flows v should be replaced by v + c . “Transient flow calculations with PISO” or “Transient flow calculations with SIMPLE” in this volume for information and advice. if any changes are needed to these parameters after your load steps have been defined.trns. A good way of testing the sufficiency of the time step size is by calculating the Courant number Co. If there is any need for alterations. Solution procedure outline The overall task of setting up parameters for a load-step based transient calculation can be divided into the following steps: Solution controls Step 1 Start up the STAR GUIde system and then define the type of problem you are solving by selecting Transient from the Time Domain pop-up menu in the “Select Analysis Features” panel. Note that this information is stored for each load step in file case. the user should calculate the Courant number in two ways: 1. you will need Version 4. Globally. cell diagonal). consult Chapter 1.g. pipe length in pipe flow). Step 3 Display the “Primary Variables” panel and check that the solution parameter settings are appropriate for your case. The time step should be chosen so that it is commensurate with the time scale of the physical process being modelled. The user should inspect the time steps derived in these two ways and select the smallest one for use in the analysis. 2. Step 2 Go to the Solution Controls folder and open the “Solution Method” panel. Select the numerical algorithm to be used (see topic “Transient problems”). by setting v to an estimated local velocity and l to the corresponding local mesh dimension (e. Note that a number of different files can be utilised in a given run.). Type the maximum load step number that will be specified in the text box provided and then click Initialize to set up a file (case. Commands: 5-10 TRFILE LSTEP LSLIST LSSAVE Version 4. click the Connect action button to retrieve existing load step information. distribution and length of time steps. but is used only in transient problems. pro-STAR’s built-in file browser may be used to locate the required file(s).02 .e.CONTROL FUNCTIONS Analysis Controls for Transient Problems Chapter 5 to retrieve the load step information.trns file (see the description of Step 4 and Step 5 below) Load step controls Step 4 Choose Modules > Transient from the menu bar to activate the Advanced Transients dialog shown below.trns) for storing all transient history information (i. changes in boundary conditions. For a restart run.mdl) file. Select option Advanced Transients On by clicking the action button at the top right-hand side of the dialog. a revised maximum load step number should be typed in the box provided. as specified in the Transient File text box. by first clicking Disconnect to release the current file and then connecting to a new one. This is a binary file that works very much like the normal pro-STAR problem description (. etc. If necessary. make the changes and then save the information back in the . The file’s name is entered in the Transient File text box. Any number typed in the text box will be available to the subroutine as a default value. or BCDEFW. Modification of selected boundary values. Option Euler Implicit selects the (default) first-order Euler implicit scheme while Three Time Level Implicit selects the second-order three-time-level implicit scheme.02 5-11 . 4. (e) Output frequency of print and post-processing data (see “Output controls” below). (d) A choice of step or ramp setting for changes in the boundary conditions (note that the ramp setting cannot be chosen if the User option is already selected in step (c) above). BCDEFS. 2. Step 6 Supply in a sequential manner all information needed to completely define each load step. without changing the boundary type. The current load step should be indicated by highlighting it in the scroll list with the mouse. pro-STAR will look for time increment definitions in user subroutine DTSTEP. Your choice of the time differencing scheme should be confirmed by clicking Apply. Any region not covered in this way will take on the usual ramp or step variation specified during the basic load step parameter setting.g. (b) Number of time steps. Remember that in cases where the boundary conditions are to vary linearly from the Version 4.Chapter 5 CONTROL FUNCTIONS Analysis Controls for Transient Problems LSCOMPRESS MVGRID TDSCHEME CDTRANS LSRANGE CPRINT CPOST LSGET CPRANGE SCTRANS LSDELETE WPRINT WPOST Step 5 If the SIMPLE solution algorithm has been chosen. The desired variation should be calculated in the appropriate user subroutine (BCDEFI. other than step-wise or ramp-wise — see option User in the section on “Boundary Region Definition” on page 4-7. The required information depends on the time-varying character of the problem and can consist of: 1. Unusual boundary value changes. Basic parameters of the load step — type these in the text boxes underneath the load step list. changing from wall to outlet boundary conditions and vice versa to simulate the operation of an exhaust valve in a reciprocating engine — see “Boundary Region Definition” on page 4-5. (c) Time increment per time step — if the option button next to this text box is selected. BCDEFT. BCDEFP. as shown in Figure 5-1 — see page 4-7 in the section on “Boundary Region Definition”. The latter gives more accurate solutions but requires more computer time and memory. e. These routines should supply the required values at every time step and for all boundary regions affected. BCDEFF. BCDEFO. i. 3. see “Boundary condition subroutines” on page 14-5). select a time differencing scheme from the Temporal Discretization pop-up menu.e. The available parameters are: (a) Load step identifying number. Redefinition of the boundary type. specify: • • The printout frequency (in terms of a time step interval) by typing a suitable value in the Print Freq. since the volume of data that can be generated is potentially very large. The cell variables (e. shear forces. text box. 5-12 Version 4. However. Step 8 Decide whether post-processing information is required. additional controls are provided to limit the amount to what is absolutely essential. • If some of the cell or wall variables to be written are additional scalar variables such as chemical species mass fraction. etc. etc. The part of the mesh over which the above quantities will be printed — type a suitable cell range in terms of starting.02 . they are specified via the Scalars Select selection button (see Chapter 13. These controls are implemented in the Advanced Transients dialog and can be sub-divided into a number of basic steps as described below. velocities. all other data for such a load step are ignored. specify: • • The output frequency (in terms of a time step interval) by typing a suitable value in the Post Freq. text box. etc. This is achieved by introducing a dummy first load step with ramp setting.) to be printed — click the appropriate Wall Print selection button underneath the desired variable(s). mass fluxes.pstt) file.) to be stored — click the appropriate Wall Post selection button underneath the desired variable(s).g.) to be printed — click the appropriate Cell Print selection button underneath the desired variable(s).g. All the above information is written to a special transient post data (.g. Note that they are part of the definition for a given load step and can be repeated as necessary during subsequent load steps to achieve the desired fine control over the type and volume of output. it is necessary to supply the boundary conditions at the start of the calculations. If so. pressure. “Multi-component Mixing”. “Multi-component Mixing”. temperature. they are specified via the Scalars Select button (see Chapter 13. pressure. Step 8). Step 8). shear forces. With the exception of the boundary condition. heat fluxes. Step 7 Decide whether printed output is required. • • If some of the cell or wall variables to be printed are additional scalar variables such as chemical species mass fraction. velocities. heat fluxes. The cell variables (e. Output controls The output to be produced by a transient run is chosen in a similar manner to that for steady-state problems. temperature. If so. The wall variables (e.g. The wall variables (e. finishing and increment cell number in the text boxes provided.CONTROL FUNCTIONS Analysis Controls for Transient Problems Chapter 5 start of the calculation. etc.) to be stored — click the appropriate Cell Post selection button underneath the desired variable(s). set the total number of load steps to be performed during the next STAR analysis by typing the starting and finishing load step number in the text boxes provided. Step 11 In addition to the load-step specific information described above. contains user-selected data. any subsequent changes made outside this box. it is advisable to give the .trns) file by clicking on the Save action button.ccm) file is as follows: • File case. • The Print and Post Freq. text box. wall heat fluxes. etc. Input data. you will need to click the Update button at the bottom of the dialog. File case. Other load step and general solution controls Step 9 Store each completed load step definition in the transient history (.Chapter 5 CONTROL FUNCTIONS Analysis Controls for Transient Problems The difference between this and the usual solution (. boundary conditions and locations. Note that all the above operations have an immediate effect on the transient settings. These form a complete set of all cell data and the file can therefore be used to restart the analysis. One monitoring cell must be selected for each different material present in the model. The desired location is specified in the “Monitoring and Reference Data” STAR-GUIde panel. To display these changes. such as cell pressures.pstt file produced at the end of each stage a unique file name. on the other hand. The file is therefore suitable for post-processing runs but cannot be used to restart the analysis. as selected from the Monitor Engineering Behaviour panels for specified grid and/or boundary regions.g by issuing commands via the pro-STAR I/O window. These options are set in the “Monitor Numeric Behaviour” panel. Confirm by clicking the Apply button. you may also request additional. However. The parameters of the saved definition are displayed in the Load Step scroll list. If the analysis is split into several stages. together with their associated print and post file operations. Step 10 Once all the necessary load steps have been defined. 5-13 • • Version 4. On the other hand. may cause excessively large data files to be written. inner iteration statistics. This includes: • Values of the field variables at a monitoring cell location at each time step.ccm contains the calculation results of only the last time step. as is usually the case with large models and/or lengthy transients. These are also produced at each time step. reflected by immediate changes to what is displayed in the dialog box. etc. e. written at predetermined points in time defined by the parameter typed in the Post Freq.02 . This helps to spread the output produced amongst several files and thus eases the data management and manipulation processes. they must not be used too sparingly as they may fail to record important data. detailed information that applies to the run as a whole. will not be shown. parameters above must be used with care since they.pstt. Various types of engineering data. Compression of the transient history file — clicking Compress eliminates all deleted steps and renumbers the remaining ones. Additional points to bear in mind about transient problems are: 1. This operation also requires either (a) a user-defined subroutine (NEWXYZ) to calculate the vertex coordinates as a function of time. These permit changes to both vertex locations and cell connectivities.02 . type values for the modified parameters and click Save. Deletion — highlight the load step to be deleted and click Delete.pstt) file and can be loaded and plotted during post-processing. using an initial and several restart runs. if additional load steps are to be specified. “Moving Meshes”). 5-14 Version 4. The modified vertex coordinates are also written to the transient post data (. Step 4 of this section. Step 14 To complete the controls specification. Other transient functions Before initiating a transient run. as defined in Step 6. in the same manner as for steady-state problems. 2. e. as described in page 5-10.g. When specifying a restart run. you need to decide whether the analysis is to start from initial conditions or restart from a previous run. However. The relevant facilities available in the Advanced Transients dialog are: • • • Modification — highlight the load step to be changed. using the “Analysis (Re)Start” STAR-GUIde panel (Standard Restart option) (b) reconnect to the transient history (. This can be done by selecting On in the Moving Grid Option pop-up menu at the top of the Advanced Transients dialog. Step 13 The total number of time steps for the run is normally equal to the sum of all time steps in each load step. by moving the mesh in a cylinder-and-piston problem. this total may be set independently via command ITER. or (b) the use of special commands provided in the EVENTS module (see Chapter 12. which may effectively stop the run in the middle of a load step.CONTROL FUNCTIONS Analysis Controls for Transient Problems Chapter 5 Step 12 Specify any other necessary controls in the Sources and Other Controls sub-folders. the user is free to review and modify the existing set of load step definitions. you must remember to (a) read in the state of the model as it was when the last run finished. Set the appropriate solution controls in the “Analysis (Re)Start” panel.trns) file. Along with time-varying boundary values and boundary conditions. you may also elect to vary the geometry of his model. An analysis can most conveniently be performed in stages. changing cell shapes. Step 1 Check the directory of your current (coarse-mesh) model to confirm that a pro-STAR model file (say.ccm) Select option Restart (Smapped) from the Initial Field Restart menus and click Apply 5-15 Version 4.g. However.ccm) exist. e.Chapter 5 CONTROL FUNCTIONS Solution Control with Mesh Changes Solution Control with Mesh Changes The discussion so far in this chapter assumes the usual condition of identical mesh geometry between restart runs. Then: • • • Select File > Case Name from the main window. approximate solution data that correspond to the re-defined mesh. STAR can read this new file and restart the analysis to obtain a proper solution for the current mesh.ccm file to create new. This requires a special mapping operation. it sometimes becomes apparent that changes in mesh geometry applied part-way through the solution process will improve the quality of the final result.mdl. refined mesh. case-coarse. “Solution Mapping” of the Post-Processing User Guide. Rather than beginning a new analysis from scratch with a new.02 . “Mesh Refinement” in the Meshing User Guide) Select File > Write Geometry File from the main window and save the refined mesh geometry in file case-fine. or even creating a mesh structure that is physically larger (or smaller) overall than the original configuration. case-fine and click Apply Perform whatever mesh refinement operations are necessary (see for example Chapter 3. Mesh-changing procedure A description of the steps necessary for performing a mesh-changing operation requiring refinement is given below. For example. coarsening. STAR-CD allows redefinition of the mesh and resumption of the analysis (via a restart run) from the currently available solution. say.mdl) and a STAR solution file (say. Note that although restarting with a refined mesh is typical. case-coarse. change the case name to. called SMAP.ccm Step 3 Signal to STAR that the next run will restart from a different (mapped) solution still to be created: • • • • Go to the Analysis Preparation/Running folder in STAR GUIde and open the “Analysis (Re)Start” panel Select option Initial Field Restart from the Restart File Option menu Accept the (default) Restart File name (case-fine. An example of the result of such an operation is given in Chapter 10. Step 2 Start a pro-STAR session and read in the coarse-mesh model from case-coarse. that utilises the existing solution data in the . inspection of the current solution file may reveal that mesh refinement is needed in some part of the mesh to resolve the flow pattern adequately. the same rules apply to any other mesh re-definition. 02 . case-fine. including the restart mode specification above: • • Select File > Save Model from the main window to save file case-fine. The SMAP operation itself is initiated by choosing Utility > Solution Mapping from the main window menu bar to display the Smap/Tsmap dialog shown below: Commands: SMAP TSMAP The required user input is as follows: 1.mdl Select File > Write Problem File from the main window to save file case-fine.ccm. This set may include both fluid and solid cells and will normally contain all cells in the model.ccm as the input file name and then clicking Open Post File Step 6 Select those coarse-mesh cells that should be used in the mapping process and put them in a cell set (see “Cell set selection facilities” on page 2-46 of the Meshing User Guide). created in Step 5-16 Version 4.mdl as the model file and click Apply Go to the Post-Processing folder in STAR GUIde and display the “Load Data” panel. This is because SMAP operates only on cells in the current set.prob Step 5 Restore the original coarse-mesh model as follows: • • • • Select File > Resume From in the main window Input the original mesh by specifying case-coarse. Input CCM file — The refined mesh file.CONTROL FUNCTIONS Solution Control with Mesh Changes Chapter 5 Step 4 Save all information for the refined mesh. Read in the coarse-mesh solution data by specifying case-coarse. If any baffles are present in the coarse-grid domain to be refined and mapped. terminate the pro-STAR session without writing a model file (as this would save the original coarse-grid data) and then run STAR to continue the analysis from the mapped solution. as defined in panel “Initialisation” of sub-folder Liquids and Gases in STAR-GUIde (b) Nearest — use values from the nearest cell neighbours (c) Zero — use a value of 0. The volume made up by the fine-grid cells should be fully contained within the volume of the coarse-grid cells. 3. Other noteworthy points are: • If option Use Tsmap is selected in moving mesh problems containing removed cells (see “Cell-layer Removal/Addition” on page 12-14). use pro-STAR’s built-in file browser to locate the file. Do not change the reference temperature in the restart run.02 5-17 . In that section. • • Solution-Adapted Mesh Changes Section “Solution Control with Mesh Changes” of this chapter shows how to transfer a solution from one mesh to another. Nearest and Zero. delete the baffles before refinement and redefine them after refinement. 3.ccm. the cell set to be mapped should not include removed cells. Step 2 simply states Version 4.0 Note that the default mapping algorithm is selected by the Use Smap button. It is not applicable to polyhedral fluid cells 2. Step 8 If the mapped results are deemed satisfactory. If necessary. This condition may be satisfied within a tolerance (specified as a volume fraction) entered in the Volume Tolerance box. Instructions on how to assign flow variable values to any fine-grid cells that may lie outside the domain defined by the coarse-grid cells. The available Outside Options are: (a) Default — use default values. The mapped solution data file just created may be accessed via the “File(s) tab” and field values loaded via the “Data tab”. Clicking the Use Tsmap button activates a slightly different algorithm that attempts to enforce global conservation on the fine-grid domain. Other ways in which this option differs from the standard option are as follows: 1. Only two Outside Options are available. The data may then be checked by plotting contours but note that only “Cell Data” should be used for this purpose. At the end of the mapping operation. Step 7 To visualise the outcome of the mapping operation. 2. case-fine. Output CCM file — The refined mesh solution file.Chapter 5 CONTROL FUNCTIONS Solution-Adapted Mesh Changes 2 above and containing only geometry data at present. use the “Load Data”panel in STAR GUIde’s Post-Processing folder. this will contain (mapped) solution data as well as geometry data and will therefore be suitable as a restart file for a fine mesh analysis. The final set can be ‘grown’. If necessary. the selection results are accumulated into a compound cell. the temperature might be a better choice. recreate the cell connectivity. This last step entails mapping the old solution to the new geometry. set • You may abandon your current selection at any stage and start again by clicking the New button Step 2 Go to the “Set Modifications” tab and select set modification options.02 5-18 . the “Refine” tab enables you to • • • refine them using a simple 2 × 2 × 2 subdivision. A typical refinement session would consist of the following steps: Step 1 Go to the Analysis Preparation/Running folder in the STAR GUIde system and open the “Adaptive Refinement” panel. Step 3 Once the required cells are finally selected. Both types of data are stored in the solution (.CONTROL FUNCTIONS Solution-Adapted Mesh Changes Chapter 5 that you need to perform whatever mesh refinement operations are necessary.ccm) file and one may then choose the flow variable and selection method to be employed. or solution residuals. to account for inaccuracies in the error estimate and to prevent large differences in refinement level between neighbouring parts of the mesh. last-minute modifications can be made to this set using the standard pro-STAR cell set utilities (see “Set Manipulation” on page 2-21). This caters for mesh refinement based on the results of a previous run. for chemical reaction. Check the set to be refined visually by plotting it. e.e. In the “Refinement Criteria” tab.dominated problems. The most frequently used refinement procedures have been assembled in the “Adaptive Refinement” panel of the STAR GUIde system. changing the solution mode to a restart run from the new (mapped) .g. This section aims to show how these changes can be made using the solution from a previous run as a guide. the velocity magnitude or the turbulence kinetic energy have been found to give good results. For flow-dominated problems. expanded to include neighbouring cells. The flow variable on which to base the refinement depends on the application. i. One may employ a refinement operation based on either • • flow variable gradients. Note that: • Using the Percent of Cells selection method allows you to closely control the number of cells selected for refinement • You may perform multiple selections based on different variables and different criteria.ccm file and redefining the monitoring Version 4. • • The Near Wall Cell Options may be used to ensure that near-wall cells are left unrefined when limitations on the magnitude of y+ need to be observed. choose a criterion by selecting the appropriate sub-tab. prepare the resulting new model for the next run. You may also choose to fill the volume with a completely new mesh built by any pro-STAR operation or imported from an external package (see “Importing Data from other Systems” on page 3-1 of the Meshing User Guide). however. concertina-style refinement.Chapter 5 CONTROL FUNCTIONS Solution-Adapted Mesh Changes and pressure reference cells. Version 4. that there are many other ways to proceed. Note. The reverse effect. coarsening the mesh. if these were within the area that has been refined. Consider filling the volume occupied by the chosen cells with one or more blocks (maybe after a little padding out) and then specifying block factors to build a mesh with progressive.02 5-19 . may by achieved via one of the above methods or by using the CJOIN command. . Chapter 6 POROUS MEDIA FLOW Setting Up Porous Media Models Chapter 6 POROUS MEDIA FLOW The theory behind flow problems of this kind and the manner of implementing it in STAR-CD is given in Chapter 8 of the Methodology volume. As an example. consider the specification of a filter in the pipe shown in Figure 6-1. “The Cell Table”). The latter contains details of the user input required and important points to bear in mind when setting up problems of this kind. This requires use of the cell table (see Chapter 3. Setting Up Porous Media Models Step 1 Index the cells in the area where distributed resistance exists. fluid material property index 12 and porous material index 11) the Cell Table Editor would look as follows: 6-1 Version 4.02 . The present chapter contains an outline of the process to be followed when setting up a porous media problem and includes cross-references to appropriate parts of the on-line Help system. cell index 1 cell index 2 cell index 1 flow in flow out filter Figure 6-1 Flow through filter in a pipe • For the non-filtered sub-domains (using cell index 1. fluid material property index 12 and porous material index 0) the Cell Table Editor would look as follows: • For the filtered sub-domain (using cell index 2. If your model contains multiple porous sub-domains possessing different properties.POROUS MEDIA FLOW Setting Up Porous Media Models Chapter 6 The reason for using an identical fluid property index (i. the Resistance and Porosity Factor panel 6-2 Version 4. Step 2 Supply property values (resistance coefficients and porosity) for the porous sub-domain using the “Resistance and Porosity Factor” STAR-GUIde panel.e. Coordinate system 5 x2 (cylindrical) x1 x1 = r 5 x x2 = θ 3 x3 = z z r 14 θ z 12 Coordinate system 1 x2 (Cartesian) x1 = x x 1 x1 x2 = y 3 x3 = z y x Honeycombs Figure 6-2 Coordinate system definition in pipe with honeycomb sections Thus. for the example shown above. each sub-domain may be selected in turn via the Porous Material # control at the bottom of the panel (see also the “Porosity” Help topic).02 . 12) is that both sub-domains are part of the same fluid domain. (x1-) direction. hence the value chosen for the resistance coefficients (7) is assigned to Alphax1 and Betax1 The porosity value (0.5) is required only for transient analyses Second honeycomb section • • • • Porous material index — 14 Local coordinate system — 5 Flow is along the θ.(x2-) direction.02 6-3 .Chapter 6 POROUS MEDIA FLOW Setting Up Porous Media Models settings for the two honeycomb sections should be as follows: First honeycomb section • • • • Porous material index — 12 Local coordinate system — 1 Flow is along the x. hence the value chosen for the resistance coefficients (7) is assigned to Alphax2 and Betax2 The porosity value (0.5) is required only for transient analyses Version 4. POROUS MEDIA FLOW Useful Points Chapter 6 Step 3 Consider whether, as a consequence of special conditions in your problem, additional input is required for each porous material. Specifically: 1. If turbulence effects are important, specify the relevant parameters using the “Turbulence Properties” STAR-GUIde panel. 2. If there is heat transfer present, specify an effective thermal conductivity and turbulent Prandtl number using the “Thermal Properties” STAR-GUIde panel. 3. If the problem requires calculation of chemical species mass fractions, the effective mass diffusivity and turbulent Schmidt number for each species need to be specified via the “Additional Scalar Properties” STAR-GUIde panel. 4. If you are doing a transient analysis, enter an appropriate value in the Porosity box (see also page 8-2 of the Methodology volume). Useful Points 1. All porous media properties can be modified by a user subroutine (PORCON, PORDIF, PORKEP, POROS1 or POROS2). 2. α and β should always be positive numbers 3. Excessive values of α and β should be avoided. In cases such as honeycomb structures where cross-flow resistances are much higher than those in the flow direction, the difference in α and β between one direction and the other should be limited to four orders of magnitude. 6-4 Version 4.02 Chapter 6 POROUS MEDIA FLOW Useful Points 4. Avoid setting β = 0 because this can cause K i → 0 as V → 0, leading to a potentially unstable situation. 5. When calculating resistance coefficients from expressions involving pressure drops, remember that the pressure drops are based on unit lengths in each direction. 6. Bear in mind the difference between velocity magnitude V and velocity component u i in your coefficient calculations. 7. Special considerations apply to modelling systems incorporating porous baffles (see “Baffle Boundaries” on page 4-23). Note that baffles may also be used to model a flow resistance at the interface between a fluid and a porous sub-domain, by placing baffles of suitable properties on the faces of the appropriate porous cells. 8. In simulations involving moving meshes, porous media must not be used in areas where there is internal relative mesh motion (cell expansion or contraction). 9. As a result of the particular method used in STAR-CD to calculate pressure gradients at cells on either side of the fluid-porous interface, you need to ensure that porous sub-domains are at least two cell layers thick in any coordinate direction. 10. Tetrahedral meshes should not be used in porous media cases. 11. For examples of porous media flow, refer to the Methodology volume (Chapter 8, “Examples of Resistance Coefficient Calculation”) and to Tutorial 3.1, Tutorial 3.2 and Tutorial 3.3 in the Tutorials volume. Version 4.02 6-5 Chapter 7 THERMAL AND SOLAR RADIATION Radiation Modelling for Surface Exchanges Chapter 7 THERMAL AND SOLAR RADIATION The theory behind problems of this kind and the manner of implementing it in STAR-CD is given in Chapter 9 of the Methodology volume. The present chapter contains an outline of the process to be followed when setting up a thermal radiation model and includes cross-references to appropriate parts of the on-line Help system. The latter contains details of the user input required and important points to bear in mind when setting up problems of this kind. Radiation Modelling for Surface Exchanges Step 1 Open the “Thermal Options” panel in STAR GUIde and select one of the following calculation methods from the Radiation menu: 1. Discrete Transfer - Internal VF Calc, making sure that option Non-Participating is also selected. 2. Discrete Transfer - FASTRAC VF Calc Continue by entering all necessary modelling parameters, as discussed in topic “Thermal Radiation”. Step 2 If present, solar radiation effects can be included by selecting Solar Radiation On and then entering all necessary modelling parameters, as discussed in topic “Solar Radiation”. Note that thermal and solar radiation calculations are independent of each other. A solar-radiation-only analysis may thus be performed without selecting any options from the Radiation menu mentioned in Step 1 above. Solar radiation may enter the solution domain through any open boundary, as well as through transparent walls; see “Solar radiation properties” on page 4-20 for a description of how the latter are specified. Step 3 Inspect the Cell Table Editor entries for cell types assigned to the medium lying between the model’s radiating surfaces and ensure their Radiation option is set to On. Step 4 In the Liquids and Gases folder: 1. Assign thermal properties to the fluid domains via the “Molecular Properties” panel 2. Turn on the temperature solver in the “Thermal Models” panel Step 5 In the “Define Boundary Regions” panel, specify surface radiative properties for all boundaries apart from symmetry and cyclic ones. To do this: 1. If only thermal radiation is modelled: (a) Specify emissivity, reflectivity and transmissivity of all wall, baffle and solid-fluid interface boundaries, as necessary. The description given in “Thermal radiation properties” on page 4-20 (for walls) and on page 4-25 Version 4.02 7-1 THERMAL AND SOLAR RADIATION Radiation Modelling for Surface Exchanges Chapter 7 (for baffles) should be read before entering values in this panel. (b) Specify the radiation temperature and emissivity at ‘escape’ surfaces, i.e. boundaries of type “Inlet”, “Outlet”, “Pressure Boundary”, “Stagnation Boundary”, “Free-stream Transmissive Boundary”, “Transient-wave Transmissive Boundary” and “Riemann Boundary”. The required values are entered in the boxes labelled T Radiation and Emissivity. Note that if the FASTRAC method has been chosen, the T Radiation value is not used. Instead, the Surrounding environment temperature specified in the “Thermal Options” panel is used to describe what lies beyond such open boundaries. Note also that the Emissivity value must be set to 0.0 2. For problems involving both thermal and solar radiation, as well as the above parameters, you also need to specify values for the solar reflectivity and transmissivity. These are required at walls, baffles, or solid-fluid interfaces. The description given in “Solar radiation properties” on page 4-20 (for walls) and on page 4-26 (for baffles) should be read before entering such values. 3. For problems involving only solar radiation, the transmissivity of wall boundaries is the only user input required. Step 6 Specify radiation patches unless your problem involves only solar radiation. Tab “Patches” in panel “Create Boundaries” contains most facilities necessary for this task. If you are using the Internal method, you may also create patches via one of the following command-driven options: 1. By specifying the face number that defines the boundary face to be included in the patch — command BDEFINE. 2. By converting a set of shells into a patch — command BSHELL Please also note that: Patches generated for use by the Internal method cannot also be used by the FASTRAC method. • The FASTRAC patch specification procedure is different from that for the Internal method. Moreover, the patches are not generated until after the view factor calculation procedure has been initiated (see Step 8 below). • ‘Escape’ surfaces do not need to be patched if the FASTRAC method has been chosen. Step 7 Check the patches created using one of the following methods: 1. Select Patch from the Cell Plot Display Options in the main pro-STAR window 2. Choose Plot > Cell Display > Boundary Patches from the main menu bar 3. Type commands BDISPLAY, PATCH or CDISPLAY, ON, BPATCH in the I/O window. The next cell plot will then display boundaries coloured according to patch number instead of according to boundary type. 7-2 Version 4.02 • Chapter 7 THERMAL AND SOLAR RADIATION Radiation Modelling for Participating Media Step 8 The action here depends on your choice of view factor calculation method: • If you have chosen Discrete Transfer - Internal VF Calc, write the geometry and problem files in the usual way and then run STAR. The view factor and any solar radiation flux calculations are performed at the start of the analysis. In moving mesh cases, view factors are re-calculated at every time step. View factors are saved in a binary file (case.vfs) and are retrieved from that file in a restart run. If you have chosen Discrete Transfer - FASTRAC VF Calc, go to the Analysis Preparation/Running folder, open the “Run Analysis Interactively” panel and start up the external program that calculates the view factors. On completion, the results are stored in file case.nvfs. Subsequent actions are as for the Internal method but using the .nvfs file instead. Note that a re-calculation of the view factors is required if either the solar radiation parameters (Step 2) or boundary transmissivity (Step 5) are altered. • Radiation Modelling for Participating Media This approach is most commonly used to model the radiative effects of a fluid filling the space between radiating solid surfaces. However, STAR-CD is also capable of calculating radiative heat transfer through transparent solid domains, which may then be treated in a similar manner to the intervening fluid. This enables you to make a realistic assessment of, for example, the effect of objects such as windows on the overall heat transfer within an enclosure. The necessary steps for participating media analysis are as follows: Step 1 1. Open the “Thermal Options” panel in STAR GUIde and select one of the following calculation methods from the Radiation menu: (a) Discrete Transfer - Internal VF Calc, making sure that option Participating is also selected. (b) Discrete Ordinates. The participating media radiation option is turned on automatically. 2. Continue by entering all necessary modelling parameters, as explained in topic Thermal Radiation 3. If your problem contains solid domains (including transparent ones) turn on the Solid-Fluid Heat Transfer option Note that inclusion of solar radiation effects is not currently possible for this type of analysis. Step 2 Using the Cell Table Editor: • • If transparent solid cells are present, index them to a separate cell type and assign a solid material number to them Select option On from the Radiation menu for all fluid and transparent solid cell types in your model 7-3 Version 4.02 THERMAL AND SOLAR RADIATION Radiation Modelling for Participating Media Chapter 7 Step 3 Go to the Liquids and Gases folder: 1. Assign thermal properties to the fluid domains via the “Molecular Properties” panel 2. Turn on the temperature solver in the “Thermal Models” panel and click Show Options. In the Participating Media section, specify bulk radiative properties (absorption and scattering coefficients) for the fluid lying between the radiating surfaces. The Conservation and Enthalpy settings in this panel do not affect the radiation solution. Step 4 If transparent solids are present, go to the Solids folder: 1. Assign thermal properties to the solid domains via the “Material Properties” panel 2. Assign radiative properties (absorption and scattering coefficients) to the solid domains via the “Radiative Properties” panel Step 5 In the “Define Boundary Regions” panel, specify surface radiative properties for all boundaries apart from symmetry and cyclic ones. Thus: • Specify emissivity, reflectivity and transmissivity of all wall, baffle and solid-fluid interface boundaries, as necessary. The description given in “Thermal radiation properties” on page 4-20 (for walls) and on page 4-25 (for baffles) should be read before entering values in this panel. Specify the radiation temperature and emissivity at ‘escape’ surfaces, i.e. boundaries by type “Inlet”, “Outlet”, “Pressure Boundary”, “Stagnation Boundary”, “Free-stream Transmissive Boundary” and “Transient-wave Transmissive Boundary”. The required values are entered in the boxes labelled T Radiation and Emissivity. • Note that: • All boundaries are assumed to be diffuse (i.e. their radiative properties are not dependent on the direction of radiation incident on or leaving the surface). • The absorptivity of the solid-fluid interface (1 - transmissivity - reflectivity) should be consistent with the absorptivity of the solid material defined in Step 4. Step 6 If you have chosen the Discrete Transfer - Internal VF Calc method, create radiation patches for all relevant boundary regions, including external boundaries of solid cells. This process is as described in “Radiation Modelling for Surface Exchanges”, Step 6 and 7. Step 7 Write the geometry and problem files in the usual way and then run STAR. If the initialization stage completes successfully, you will see an echo of the specified modelling parameters in the .info and .run files. • 7-4 If you have chosen the Discrete Transfer - Internal VF Calc method, the Version 4.02 Chapter 7 THERMAL AND SOLAR RADIATION Capabilities and Limitations of the DTRM Method • • view factor calculations are performed at the start of the analysis. In moving mesh cases, view factors are re-calculated at every time step. View factors are also saved in a binary file (case.vfs) and are retrieved from that file in a restart run. Participating media data are stored in another binary file (case.pgr) and then retrieved from it in a restart run. If you have chosen the Discrete Ordinates method, the STAR solver is called every n iterations during the run to solve the radiative transfer equation (where n is the value specified in the “Thermal Options” panel). The solver allocates and frees memory each time, which is reported. In addition, the solver prints out a residual history for the solution of the radiative transfer equation, as well as a summary of the computation. At convergence, the displayed value for the Imbalance quantity should be small compared to heat fluxes of engineering interest. This indicates that the net radiation emission from the medium equals the net absorption into the boundary. If all boundaries are adiabatic and there are no other energy source terms, both the net boundary emission and the net media emission will separately reach very small values. Capabilities and Limitations of the DTRM Method 1. Lagrangian particle radiation may be modelled by setting Constant 82 to a non-zero value equal to the particle emissivity. For coal combustion cases, this operation may be performed via the “NOx/Radiation” panel in STAR GUIde. 2. Conducting walls (solid-fluid interfaces) should have their transmissivity set to either 1 or 0, depending on whether radiative heat transfer through the solid material is to be considered. If radiation in the solid is on, the transmissivity at the solid-fluid interface must be 1, otherwise it must be 0. 3. The FASTRAC method must be used for thermal/solar radiation problems with transmissive external walls. 4. At present, the FASTRAC method does not apply to problems containing symmetry or cyclic boundary regions. 5. ‘Escape’ or open flow boundaries (inlet, outlet, pressure, etc.) require an assumption regarding the radiation passing through these boundaries and emitted from outside the solution domain. The Internal method assumes that this externally emitted radiation is coming from a surface of given temperature that coincides with the escape boundary surface. The FASTRAC method assumes that a distant ‘environmental’ black body emits radiation at a given temperature. These differing assumptions lead to slightly different results. In addition, the Internal method allows specification of different radiation temperatures at each open boundary whereas FASTRAC assumes that all open boundaries "see" the same environmental surface. 6. Radiation patches cannot be applied to boundaries assigned to the default wall region (region no. 0). If you need to turn on radiation modelling in a problem containing such boundaries, you will need to re-assign them first to a non-zero wall region number. 7. The accuracy of the radiation calculations depends on the patch size since quasi-uniform radiation properties are assumed for a patch. The accuracy of Version 4.02 7-5 11. STAR-HPC runs for problems involving both radiation and a 7-6 Version 4. the number of beams may need to be increased (between 1600 and 2500 for typical radiation problems) in order to resolve adequately the patches present in the system. 12. 13.024). User subroutine USOLAR cannot be used for solar radiation problems employing the FASTRAC method. Internal view factors for moving mesh cases are re-calculated at every time step. run the case for zero iterations on a single processor and save the view factor (. or (b) graphically (using the screen cursor) via the BCROSS command. 16. In situations where a patch is created for every boundary cell face. (b) The aspect ratios of patches should be close to 1. 8. Surface-exchange problems using the Internal calculation method can be run in STAR-HPC mode. For maximum accuracy: (a) Patches should be planar.vfs) file.02 . but the view factors have to be calculated in ‘single-processor’ mode. If the wrong patch number is assigned to a cell face during the patch definition process (Internal view factor calculations only). The FASTRAC calculation method uses a fixed number of beams (1. However. Therefore. The CPU time for Internal view factor calculations increases in proportion to the number of patches multiplied by the number of beams. The FASTRAC view factor calculations are also dependent on the number of patches but the CPU time required is considerably reduced.THERMAL AND SOLAR RADIATION Capabilities and Limitations of the DTRM Method Chapter 7 the view factor calculations depends on both the patch size and the number of beams emitted per patch.bnd) and read back from it using the normal boundary export and import facilities provided in panels “Export Boundaries” and “Import Boundaries”.0. 15. any refinement of patches should be followed by an increase in the number of beams. As stated on page 7-3. Patches defined as part of the Internal view factor calculation can be stored in a file (case. so that all patches are resolved adequately (see “Patch and beam definition” on page 9-2 of the Methodology volume for a discussion of this point). acceptable results may be obtained even if one or more of the above conditions are not fully met. The default number of beams used in the Internal view factor calculation process (100) may be sufficient for coarse patches. 14. (c) If you are using the Internal view factor calculation method. The CPU time for radiation heat transfer calculations increases in proportion to the number of patches. the mistake can be rectified either: (a) numerically via the BMODIFY command. respectively. STAR-HPC runs are not feasible for problems involving participating media radiation. STAR-HPC runs for problems involving solar radiation are only feasible if the FASTRAC method has been chosen. Step 8 above. in view of the previous restriction. (d) Patches should not span multiple regions unless the assumption of quasi-uniform radiation properties is valid over those regions. To do this. 10. 9. etc. Although the radiative transfer equation is similar to a normal transport equation. The model may be run in the normal way under STAR-HPC. Nevertheless. baffle cells. converged solutions in serial and HPC calculations are identical. 17. For this reason. Note also that FASTRAC view factor calculations cannot be used in moving mesh cases at present. The discrete ordinates model (DORM) does not need radiation patches and the computational overheads involved in their use. non-participating media analyses). a specialized solver that follows the directions of each ordinate is used. The table below gives a guide to memory usage per 100. some domains may receive the information about certain directions only after it has crossed through the other domains.000 cells 45 MB 55 MB 75 MB 95 MB 4. Note that command PATCH generates only shell surfaces. using DORM can still add significantly to the CPU time and memory needed for a given simulation. .000 cells. STAR will accept geometry files with or without patches. Capabilities and Limitations of the DORM Method 1. DORM can also be used to model surface-exchange problems (i. users are encouraged to plan their analyses conservatively until they gain experience with the CPU time and memory requirements of their model. Nevertheless. 5. the solution history for a serial run will be different from that for a parallel run. Coupling between the ordinate directions at cyclic and symmetry boundaries approximates such boundaries as diffuse.) 7. Since the participating media mode is Version 4. there is no equivalent of the diffusion term and so the equation is not elliptic. 3. It cannot be used to create radiation patches. Note that this holds for single-precision calculations and a grey medium. The run-time output for the DORM calculation will echo the memory requirements (see Step 7 above). However. Table 7-1: Approximate memory required for DORM analysis Ordinates 8 24 48 80 Angular discretization S2 S4 S6 S8 Additional memory per 100. The memory requirements of the calculation depend on your choice of angular discretization. 2. in the STAR-HPC environment.02 7-7 . 6. DORM is fully compatible with all cell shapes supported by pro-STAR (polyhedral cells.Chapter 7 THERMAL AND SOLAR RADIATION Capabilities and Limitations of the DORM Method moving mesh are not feasible. to facilitate switching from a discrete transfer (DTRM) to a discrete ordinate (DORM) model for the same problem. To solve this equation efficiently. In addition. Thus.e. DORM does not support cases involving solar radiation.Internal VF Calc or the Discrete Ordinates option in the Radiation menu and then specify all necessary radiation parameters.Internal VF Calc method (whether Participating or Non-Participating). Step 5 If you have chosen the Discrete Transfer . • • 7-8 Version 4. Step 4 Within the radiative sub-domain. create patches on all boundaries surrounding the radiative sub-domain. no further action is necessary. when doing a complete continuum mechanics analysis around a car body. where radiation calculations are only necessary under the car bonnet. e. create the necessary number of special ‘Radiation’ boundaries so as to completely separate the radiative from the non-radiative part of the domain. turn on the radiation calculations by selecting either the Discrete Transfer . use the “Define Boundary Regions” panel to specify radiation properties for all boundary regions. as described in “Radiation Modelling for Surface Exchanges”. turn the Radiation option On Step 3 The action here depends on your choice of method in Step 1 above: For the Discrete Transfer . radiation effects are important only within a restricted sub-domain of the overall solution domain. including the radiation boundaries. The following steps are then necessary: Step 1 In the “Thermal Options” STAR GUIde panel. At present.g.02 . radiation boundaries are not applied.Internal VF Calc method. Step 6 Write the geometry and problem files in the usual way and then run STAR. • For the Discrete Ordinates method. “Radiation Boundaries”). Step 2 Using the Cell Table Editor: Create a separate cell type for all cells occupying the sub-domain that is subject to the radiative treatment • For this cell type only. Step 2 above is all that is required to define the problem properly. it is possible to confine the radiative heat transfer treatment to the part of the model where it is relevant. including the special boundaries created above (see also Chapter 4. 8. Radiation Sub-domains In some problems.THERMAL AND SOLAR RADIATION Radiation Sub-domains Chapter 7 always on. the absorption and scattering coefficients must be set to zero for such cases. Under such circumstances. thus avoiding the lengthy calculations needed for a full radiation analysis. Regress variable models are normally used in engine combustion simulation and are described separately in Methodology Chapter 11. of the type mentioned above (c) Regress Variable. The reactions may be sub-divided into the following groups: (a) Local Source. Partially Premixed — combustion of this type is one of the essential features in Gasoline Direct Injection engines. Unpremixed/Diffusion — reactions of this type occur when the fuel and oxidant streams enter the solution domain separately.C. A set of recently implemented engine combustion models is discussed in the section on “Setting Up Advanced I. as in a spark ignition engine (a) Local Source. Homogeneous reactions are grouped into three distinct types: 1. In some cases.Chapter 8 CHEMICAL REACTION AND COMBUSTION Introduction Chapter 8 CHEMICAL REACTION AND COMBUSTION STAR-CD allows for two kinds of chemical reaction: • • Homogeneous — the reaction occurs within the bulk of the fluid Heterogeneous — the reaction takes place only at surfaces. Engine Models” on page 8-22 of this chapter. represented by various eddy break-up and flame-area models (see “Regress Variable Models” on page 8-10 for more details) The theory behind reaction models of the local source. complex chemistry and PPDF type is described in Chapter 10 of the Methodology volume. chemical kinetic. where combustion occurs in a non-uniform mixture. of the type mentioned above (c) Regress Variable. as in a Diesel engine. Premixed — reactions of this type occur when the fluid initially has a uniform composition. of the type mentioned above (b) Complex Chemistry. the model describing the main chemical reaction(s) may need to be supplemented by subsidiary models that describe: Version 4. such as in catalytic converters Introduction Heterogeneous reactions are currently implemented via user-supplied subroutines. of the type mentioned above (b) Complex Chemistry. The reactions may be sub-divided into the following groups: (a) Local Source — these include eddy break-up. and hybrid models (see “Local Source Models” on page 8-2 for more details) (b) Complex Chemistry — these model the reaction system by including the full reaction mechanism (see “Complex Chemistry Models” on page 8-11 for more details). represented by a Flame Area Evolution (FAE) model 3. (c) Presumed Probability Density Function (PPDF) — these include single and multiple fuel implementations and the Laminar Flamelet model (see “Presumed Probability Density Function (PPDF) Models” on page 8-3 for more details) 2.02 8-1 . However. it is the user’s responsibility to ensure that boundary conditions for both leading reactant and 8-2 Version 4. STAR-CD automatically sets up mixture fraction scalars for each leading reactant in diffusion and partially premixed reactions. they need to be explicitly assigned to a domain before they can be used in your simulation. as discussed in “NOx Modelling” on page 8-39. 5. such as engine knock All these models together constitute a so-called chemical reaction scheme. The remaining reacting species are defined as reactants. Special considerations apply to modelling coal combustion. typically NOx products. Application Specific models. see “Diffusion reaction / non-homogeneous systems” on page 10-5). 4. However. Note that: • • Chemical schemes are defined and numbered individually Chemical scheme definitions can exist independently of any fluid domains or scalar variables. If this is not the case. as appropriate. However. Each reaction is associated with a single chemical species designated as the leading reactant (equivalent to fuel in a combustion reaction). these are discussed in the section on “Coal Combustion Modelling” on page 8-41. • • Local Source Models The main characteristics of this group of models are as follows: 1. Special considerations apply to modelling NOx-type reactions. 6. However.02 . The reactions are irreversible 3. provided that the products are generated only within the domain. This species characterises the reaction and is consumed by it. (b) if a product is transported into the solution domain from an external source. The distribution of products within the solution domain can be calculated algebraically. this association may be changed by the user to suit problem requirements or to try out alternative reaction models. it should be specified as a leading reactant or ordinary reactant. it also should be specified as a reactant. Each fluid domain may be associated with only one chemical reaction scheme. If all incoming streams consist of identical fuel-to-reactant ratios (in transient cases the initial fields must also have the same ratio). the process is either of the diffusion or the partially premixed type and the user needs to solve an additional scalar transport equation for the mixture fraction (total mass fraction of burned and unburnt fuel. 7.CHEMICAL REACTION AND COMBUSTION Local Source Models Chapter 8 • • • Ignition mechanisms Emission of pollutants. The products of a reaction are defined as products. Up to 30 chemical reactions may be defined per scheme 2. (a) if a product of a reaction participates as a reactant in a second reaction. the reaction process is termed premixed (see “Premixed reaction/homogeneous systems” on page 10-4 of the Methodology volume). For example. where two types of fuel and one type of oxidiser are present.Chapter 8 CHEMICAL REACTION AND COMBUSTION Presumed Probability Density Function (PPDF) Models mixture fraction are specified correctly and that they are the same for both of them. There is a choice between equilibrium chemistry models (these assume a local instantaneous chemical equilibrium) and a laminar flamelet model that allows for non-equilibrium effects (such as flame stretch). though each of these may enter the combustion system through more than one inlet. where only one type of fuel and one type of oxidiser are present. By expressing all instantaneous values of the variables as polynomials of the mixture fraction and then doing the integration analytically. the PDF integration may be performed in two ways: 1. the input required for the following reaction (combustion of methane) CH 4 + 2O 2 → CO 2 + 2H 2 O is Reaction (1) Leading reactant (fuel) (1) Reactant (1) Product (1) Product (2) kmol 1 2 1 2 (8-1) — — — — CH 4 O2 CO 2 H2 O 9. This is an auxiliary program that computes the chemical Version 4. Presumed Probability Density Function (PPDF) Models Models of this type are described in Chapter 10. pro-STAR includes facilities for checking that mass is conserved for each reaction. 6]. The reactions themselves are defined by specifying the amounts (in kilomoles) of the participating leading reactants. Polynomial coefficients may be (a) supplied by the user (b) read in from a built-in database stored in file ppdf. These fall into two main groups: • Single-fuel PPDF. • Single-fuel PPDF The basic equations solved are for the mean mixture fraction f and its variance g f (see Chapter 10. 8. Multiple-fuel PPDF. “Single-fuel PPDF” in the Methodology volume). By employing a numerical integration technique 2.dbs (c) calculated by the CEA (Chemical Equilibrium with Applications) program [5. Equilibrium models In these models.02 8-3 . reactants and products. “Presumed-PDF (PPDF) Model for Unpremixed Turbulent Reaction” in the Methodology volume. The setup procedure for the model is described in the on-line Help for the “Reaction System” STAR GUIde panel. There is also a choice between an adiabatic and a non-adiabatic model. One part of this procedure is to specify the reaction mechanism. Note that these polynomials are based on molar fractions. Each element and isotope must be declared using a one. an electron must be declared as the element E. the PDF integration is always performed numerically and the results stored in a look-up table which is characterised by its mean mixture fraction. as above. For non-adiabatic PPDF. Any line or portion of a line starting with an exclamation mark (!) is considered a comment and will be ignored. For adiabatic PPDF: (a) The mixture density and temperature are calculated numerically or from polynomials in f. The mass fractions of all other chemical species related to the reaction are defined as additional scalar variables and calculated numerically or from the user-supplied polynomials in f. The symbols may appear anywhere on a line. but those on the same line must be separated by blanks. Any number of element symbols can be written on any number of lines. then only the symbol identifying it need appear 8-4 Version 4. This program is included in the STAR-CD suite and is used in conjunction with the built-in PPDF model.g. the density is calculated from the ideal gas law and the temperature from the enthalpy transport equation. Up to forty eight such species can be specified by the user. There is also a choice between adiabatic and non-adiabatic PPDF: 1. mixture fraction variance and strain rate.or two-character symbol. If an ionic species is used in the reaction mechanism (e.CHEMICAL REACTION AND COMBUSTION Presumed Probability Density Function (PPDF) Models Chapter 8 equilibrium composition of a mixture. (b) Since temperature is calculated independently. Laminar flamelet model In this model. Blank lines are also ignored. The purpose of the element data is to associate the element atomic weights with their character symbol representations. stored in a reaction definition file in CHEMKIN format. the ‘Constant’ specific heat property option with default values may be used 2. Element Data All chemical species in the reaction mechanism must be composed of chemical elements or isotopes of chemical elements. This is organized in three sections: • • • Element data Species data Reaction data The basic data are often supplemented by auxiliary data for special reactions such as third-body reactions. OH+).02 . there are minimal restrictions on the formatting of the rest of the section. If an element is in the list below. following that. Element data must start with the word ELEMENTS (or ELEM) but. as above. as described in Table 8-1.014/. W. TI. TL. BR. S. AR. The atomic weight may be given in integer. ND. CE. For example. FR. AS. sec and K. TC. ES. The recognized elements are as follows: H. RU. BE. SR. MG. sec and K. OS. IN. BI. BK. DY. RN. SE. NP. NI. An acceptable format for species data specification is shown below: SPEC H2 O2 H O OH HO2 H2O Reaction Data The reaction mechanism may consist of any number of chemical reactions involving the species named in the species section. KR. RA. SN. molecules. The lines following the REACTIONS line contain reaction definitions together with their Arrhenius rate coefficients. which are case sensitive. CD. AC. the atomic weight must follow the identifying symbol and be delimited by slashes (/). PU. O. TB. NA. I. AT. RH. N. the atomic weight of an element in the above list may be altered by including the atomic weight as input just as though the element were an isotope. PA. β R and E R from the general Arrhenius rate equation for the forward reaction. CM. ZN. ZR. ER.Chapter 8 CHEMICAL REACTION AND COMBUSTION Presumed Probability Density Function (PPDF) Models in the element data. SM. E For an isotope. RB. C. Species data must start with the word SPECIES (or SPEC) but. A reaction may • • • be reversible or irreversible. HF. On the same line. EU. B. Y. GA. LA. PO. The rate of each reaction is defined by specifying A R . the isotope deuterium may be defined as D/2. TH. TE. TM. subsequent formatting of this section is not particularly important. CS. XE. PM. CO. AG. AL. Any set of up to 16 upper or lower case characters can be used. be a three-body reaction with an arbitrary third body and/or enhanced third-body efficiencies. LU. CU. CF. HG. The default units for E R are cal/mole and the default units for A R are cm. JOULES/MOLE. NE. FM. see equation (10-65) in the Methodology volume. or EVOLTS.014/ O N END! END is optional Species Data Each chemical species in a reaction must be identified on one or more species line(s). D. MO. YB. K. FE. TA. MN. KELVINS. The description is Version 4. In addition. mole. Reaction data must start with the word REACTIONS (or REAC). F. HO. each species must be composed of elements that have been identified in the element data section. GD. PR. GE. BA. U. KCAL/MOLE. KJOULES/MOLE. CR. but internally it will be converted to a floating-point number. HE. AM. you may specify units of the activation energies to follow by including the word CAL/MOLE. RE. An acceptable format for element data specification is shown below: ELEMENTS H D /2. have one of several pressure-dependent formulations. AU. CA. NB. SC. Including the word MOLECULES on the REACTIONS line changes the units of A R to cm. IR. or “E” format. If desired. PD. as for species names.02 8-5 . SB. P. SI. floating-point. CL. LI. as already discussed. V. PB. PT. CHEMICAL REACTION AND COMBUSTION Presumed Probability Density Function (PPDF) Models Chapter 8 composed of reaction data and optional auxiliary information data. Non-integer coefficients are allowed. not the total concentration M. => Special Symbols An M as a reactant and/or product stands for an arbitrary third body. Version 4. in which case auxiliary data (described below) must follow the reaction line. e. The coefficient’s meaning is that there are that many moles of the particular species present as either reactants or products. It should appear as both a reactant and a product. An M as a reactant and product surrounded by parentheses indicates that the reaction is pressure-dependent. Table 8-1: Species Symbols Each species in a reaction is described by a unique sequence of characters.02 +M (+M) ! 8-6 . 2OH. CH4). the comment may be used to give a reference to the source of the reaction and rate data. Coefficients A species symbol may be preceded by an integer or real coefficient. In a reaction containing an M. but the element balance in the reaction must still be maintained. An equality sign is the delimiter between the last reactant and the first product in a reversible reaction. (+H2O) indicates that water is acting as the third body in the fall-off region. For example. An equality sign with an angle bracket on the right is the delimiter between the last reactant and the first product in an irreversible reaction. as they appear in the species data (e. certain species can be specified as having enhanced third-body efficiencies.g.g. Delimiters + = A plus sign is the delimiter between each reactant species and each product species. is equivalent to OH + OH. An exclamation mark means that all following characters on the reaction line are comments. all species act equally as third bodies and the effective concentration of the third body is the total concentration of the mixture. A species may also be enclosed in parentheses. For example. in which case auxiliary information line(s) (described below) must follow the reaction to identify the fall-off formulation and parameters. If no enhanced third-body efficiencies are specified. Third-Body and Pressure-Dependent Reaction Parameters If a reaction contains M as a reactant and/or product.000 3800 ! example of real coefficients END ! END statement is optional. 3.5H2O2 + 0. Their units are as specified in the REACTIONS line above. Three Arrhenius coefficients ( A R .720 0. Comments are any characters following an exclamation mark.670 6290 HO2 + H2 = H2O2 + H 1. All blank spaces. or “E” format).60E+12 0.25E+13 0.. floating point. An example of reaction data for a simple mechanism is shown below: REACTIONS CAL/MOLE H2 + O2 = OH 1.61E+17 -0. or “E” format (e. 123. 2.300 3626 H + O2 = HO2 3.000 0 0. auxiliary information lines may follow the reaction line to specify enhanced third-body efficiencies of certain species.000 47780 OH + H2 = H2O + H 1. For all pressure-dependent reactions. one or more auxiliary information lines must follow to define the pressure-dependence parameters.06E+04 2. β R and E R . separated from each other and from the reaction description by at least one blank space. The three numbers must be separated by at least one blank space and be given in integer. 123. β R and E R ) must appear in order on each line.g. 7. are ignored.0 or 123E1). no blanks are allowed within the numbers themselves. No more than six reactants or six products are allowed in a reaction. Auxiliary Reaction Data The format of an auxiliary information line is a character-string keyword followed by a slash-delimited (/) field containing an appropriate number of parameters (in either integer.70E+13 0. in that order. 5. followed by an example: 1. and may include units definition(s).5H2 = H2O 1. Different types of auxiliary reaction data are described below. 6. Each reaction description must have = or => between the last reactant and the first product. 4. If a pressure-dependent reaction is indicated by a (+M) or by a species contained within parentheses. Each reaction description must be contained within one line. except those between Arrhenius coefficients. A species that acts as an enhanced third body must be declared as a species. an auxiliary information line must follow to specify either the low-pressure limit Arrhenius parameters (for fall-off reactions) or the high-pressure limit Arrhenius parameters (for chemically Version 4. and its single parameter is its enhanced efficiency factor. The reaction description can begin anywhere on the line. say (+H2O). The basic rules for specifying reaction data are summarised below: 1. floating point. The first line must start with the word REACTIONS (or REAC).17E+9 1.Chapter 8 CHEMICAL REACTION AND COMBUSTION Presumed Probability Density Function (PPDF) Models The second field of each reaction line is used to define the Arrhenius rate coefficients A R . The keyword defining an enhanced third-body efficiency is the species name of the third body.000 O + H2 = OH + H 5. At least one blank space must separate the first number and the last symbol in the reaction.02 8-7 . c and d. with the three rate parameters A ∞ . in this case. the keyword LT must be followed by two parameters — the coefficients B R and C R from equation (10-81) in the Methodology volume. then by default d = 1 and e = 0 . The fourth parameter is optional and if omitted. b. 2. (c) To define an SRI pressure-dependent reaction. the keyword SRI followed by three or five parameters must be included in the following order: a. although this is used to indicate that the reaction is pressure dependent in other cases. the keyword HIGH must appear on the line. the last term in equation (10-77) is not used. This particular option for describing pressure-dependent reactions cannot be combined in any given reaction with other options for describing pressure dependence. β 0 and E 0 . the three 8-8 Version 4. although rate parameters need to be supplied on the main reaction line to prevent an error. In this case. c. The units of the rate parameters provided with the PLOG keyword should match the units used for the overall reaction description. If the rate expression at a given pressure cannot be described by a single set of Arrhenius parameters. The supplementary lines need to be in order of increasing pressure. with three rate parameters A 0 . Reverse Rate Parameters For a reversible reaction.There are then three possible interpretations of the pressure-dependent reaction: (a) Lindemann formulation . For fall-off reactions. and E R are taken from the numbers specified on the reaction line itself. 3. Landau-Teller Reactions To specify Landau-Teller parameters. If reverse parameters are specified in a Landau-Teller reaction via REV (see item 4 below). The fourth and fifth parameters are optional. For chemically activated bimolecular reactions. Each of these should be followed by the keyword DUPLICATE. as defined in equation (10-77) of the Methodology volume. those values are superseded by the ones provided on the supplementary lines. in addition to the LOW or HIGH parameters.CHEMICAL REACTION AND COMBUSTION Presumed Probability Density Function (PPDF) Models Chapter 8 activated reactions). with the keyword RLT and two coefficients B R and C R for the reverse rate. the reverse Landau-Teller parameters must also be defined.in addition to the LOW or HIGH parameters. Logarithmic Interpolation of Pressure-Dependent Rates This generalized way of describing the pressure dependence of a reaction rate is indicated by the PLOG keyword in auxiliary lines. the reaction description should not include (+M) in it. Here. 4. auxiliary data may follow the reaction to specify Arrhenius parameters for the reverse-rate expression.02 . If only the first three are stated. as defined in equation (10-79) of the Methodology volume. the keyword TROE followed by three or four parameters must be included in the following order: a. meaning the sum of the sets of rates provided for a given pressure will be used. the keyword LOW must appear on the line. β R . One supplementary line starting with the PLOG keyword needs to be supplied for each pressure in the set. β ∞ and E ∞ . The Arrhenius parameters A R . Note that. d and e. more than one set may be provided. b. The keyword is followed by slash-delimited values for the pressure (in atmospheres) and the rate parameters for that pressure.no additional parameters are defined (b) Troe formulation . An example of the use of auxiliary reaction data for a three-parameter Troe fall-off reaction with enhanced third-body efficiencies is shown below: CH3+CH3(+M)=C2H6(+M) 9. you should employ the auxiliary keyword UNITS. Only an equilibrium chemistry model is available in this case 3.18 654 LOW / 3. the use of vitiated air containing combustion products is a viable option. and E R ) for the reverse rate must follow the keyword REV. for the progress variables f p (primary fuel mixture fraction). which assumes that only fuel and air enter the system. or EVOLTS. as described by equation (10-66) in the Methodology volume. The basic PPDF model. see Chapter 10. additional boundary conditions need to be defined for them. 6. 2. g f (primary fuel variance) and g ξ (variance of variable ξ. CAL. respectively. Note that the temperature units in the rate expression are always in Kelvin. The PDF integration is always performed numerically Other noteworthy points about PPDF models are: 1. 5. STAR-CD’s implementation has been extended to allow up to four dilutants to enter the combustion system. KELVIN. β R .03E16 -1.02 8-9 . therefore. This keyword must be followed by one or more of the following unit descriptors: MOLECULE. “Multiple-fuel PPDF” in the Methodology volume). additional transported scalars are defined to represent the dilutants. for forward and reverse reaction descriptions. cannot be used for this kind of problem. / H2/2/ CO/2/ CO2/3/ H2O/5/ Multiple-fuel PPDF 1. JOULE. In such a case. The remaining unit descriptors specify the energy units in the rate expression. Reaction Order Parameters Auxiliary data may be included to override the reaction order for a species. Version 4.03 2762 / TROE / 0. KJOULE. using the auxiliary keywords FORD or RORD. The basic setup is the same as that used for the standard PPDF model.6041 6927 132.18E41 -7. However. Four equations are solved. KCAL. In order to increase the efficiency of combustion systems by increasing the temperature of incoming oxidisers. f s (secondary fuel mixture fraction). However. Reaction Units It is sometimes convenient to specify units for a particular reaction rate fit that differ from the default units specified for other reaction expressions in the chemistry mechanism. This option overrides the reverse rates that would be normally computed by satisfying microscopic reversibility through the equilibrium constant. This option overrides the stoichiometric coefficients for the species included in the auxiliary data. Each occurrence of these keywords must be followed by the species name and the new reaction order.Chapter 8 CHEMICAL REACTION AND COMBUSTION Presumed Probability Density Function (PPDF) Models Arrhenius parameters ( A R . The inclusion of MOLECULE would indicate that the reaction rate expression is in units of molecules/cm3 rather than mole/cm3. The regress variable b defined by equation (11-4) in the Methodology volume is the transported variable and is a passive scalar 2. The remaining reacting species are defined as reactants. equilibrium chemistry model plus the non-adiabatic PPDF option. STAR-CD automatically sets up mixture fraction scalars for each leading reactant in diffusion and partially premixed reactions. it is the user’s 8-10 Version 4. The only regress variable model that may be used in partially premixed systems is the Weller 3-equation model. the process is of the partially premixed type. Regress Variable Models Models in this group solve a transport equation for a regress variable representing the combustion process and are described in the Methodology volume. 4. which is either obtained from an algebraic relationship given by equation (11-36) or from the solution of a transport equation ii) “The CFM-ITNFS model” — employs a transport equation for the flame area density Σ. 7. 6. 2. used in a manner similar to that described above under “Local Source Models”. If this is not the case.CHEMICAL REACTION AND COMBUSTION Regress Variable Models Chapter 8 It is emphasised that PPDF with dilutants can only be used in conjunction with the single-fuel. The reaction is irreversible and is defined by specifying the amounts (in kilomoles) of the participating leading reactants. given by equation (11-10) iii) “The Weller 3-equation model” — requires the solution of equations for both wrinkling factor and mixture fraction iv) All have their own ignition models (b) Eddy break-up models. The one-step reaction representing the combustion process is associated with a single chemical species designated as the leading reactant (or fuel). If all incoming streams consist of identical fuel-to-reactant ratios (in transient cases the initial fields must also have the same ratio). However. Their main features are: 1. i. discussed in sections “Premixed Combustion in Spark Ignition Engines” and “Partially Premixed Combustion in Spark Ignition Engines” of the Methodology volume: i) “The Weller flame area model” — makes use of the wrinkling factor Ξ. an additional scalar transport equation for the mixture fraction needs to be solved. The multiple-fuel PPDF option may also be used to model a system containing only one type of fuel but two different types of oxidiser.02 . This species characterises the reaction and is consumed by it. reactants and products. Regress variable models may be classified into two groups: (a) Flame-area models. 8. pro-STAR includes facilities for checking that mass is conserved. All physical scalar variables participating in such schemes are linearly related to b 3.e. Chapter 11. the reaction process is termed premixed (see “Premixed reaction/homogeneous systems” on page 10-4 of the Methodology volume). 5. 1. a reaction mechanism file called cplx. There is no ‘+’ character between the pre-exponential factor. ‘⇒’ for irreversible reactions. … are the mass fraction exponentials.2E05. so that users can ensure settings have been correctly applied. Character ‘=’ is used for reversible reactions. … are the stoichiometric coefficients which could be integer or real numbers. m 1 ″ .inp02. n 2 ′ . …. … are species names. A. Rules: • • There are no spaces between stoichiometric coefficients n i ′ . Everything following the ‘!’ character is treated as a comment The ‘+’ character should not be used in a real number expression. The maximum number of reactants or products in a single reaction must not exceed 5 8-11 • • • • • Version 4.inp&&-echo for each cplx. they are not written into the corresponding echo file (cplx. β and E are separated by at least one blank space. n i ″ and species names. n 2 ″ .inp&& has to be created by the user for each chemical scheme in which a complex chemistry model is applied. For example. m 2 ′.inp&& file it has read.inp&& contains the reaction formula. …. One of them is the CHEMKIN format. R 2 . Complex Chemistry Models The complex chemistry model supports two types of format for reaction mechanism definition. and the nearest species name. β the temperature exponent and E the activation energy of the Arrhenius rate constant (in cal/mol). If n i ′ or n i ″ are equal to 1. “Exhaust Gas Recirculation” in the Methodology volume). If the value of m i ′ or m i ″ is not specified.Chapter 8 CHEMICAL REACTION AND COMBUSTION Complex Chemistry Models responsibility to ensure that boundary conditions for both leading reactant and mixture fraction are specified correctly and that they are the same for both of them. they can be omitted. R 1 . the reaction mechanism file should be called cplx. File cplx. if such a model is applied in chemical scheme no. 9. STAR will write an echo file cplx.inp&&-echo). it will be assumed that m i ′ = n i ′ or m i ″ = n i ″ . 2. P 1 . P 2 .02 . m 2 ″ . In order to use STAR-CD’s complex chemistry model. n 1 ″ . If the mass fraction exponentials are equal to 1. For example. chemical kinetic data and keywords and extra parameters for special reactions. A is the pre-exponential factor (in units of cm-mole-sec-K). n 1 ′ . The characters ‘&&’ at the end of the file name represent the chemical scheme number in which the complex chemistry model is applied. the other the STAR-CD native format described below. m i ′ and m i ″ must be separated by at least one space from the species name. …. A. as outlined below: Reaction formula definition The general form of a reaction formula is given by n1 ′ R1 m1 ′ + n2 ′ R2 m2 ′ + … = n1 ″ P 1 m1 ″ + n2 ″ P 2 m2 ″ + … A β E Here. Exhaust gases present in EGR (Exhaust Gas Recirculation) systems are taken into account by defining active scalars for each exhaust gas species and solving additional transport equations for their mass fraction (see also Chapter 11.2E+05 should be written as 1. m 1 ′. e. add two lines starting with keywords LOW and TROE. and E L are the pre-exponential factor. / LOW / A L β L E L 8-12 Version 4. They are separated by at least one blank space. The Landau-Teller reaction To define a Landau-Teller reaction. respectively. β L . i. add a line starting with the keyword RLT after the normal reaction formula. add a line starting with the keyword LOW after the reaction formula. / LOW / A L β L E L Rules: • • Keyword LOW must be enclosed by two ‘/’ characters and is not case sensitive A L . after the reaction formula. add a line starting with the keyword M after the reaction formula. / RLT / B C Rules: • • • Keyword RLT must be enclosed by two ‘/’ characters and is not case sensitive B and C are the Landau-Teller parameters and are separated by at least one blank space If the reaction is a three-body reaction as well. … are species names and α 1 . α 2 . a new line is added starting with ‘ / M / ’ and the third body efficiency factors The Lindemann fall-off reaction To define a Lindemann fall-off reaction. a new line is added starting with ‘ / M / ’ and the third body efficiency factors • • The Troe fall-off reaction To define a Troe fall-off reaction.02 .CHEMICAL REACTION AND COMBUSTION Complex Chemistry Models Chapter 8 Three-body reaction definition To define a three-body reaction. respectively. B.e. i.e. temperature exponent and activation energy. of the low pressure limit and are separated each from each other by at least one blank space The corresponding values for the high pressure limit are assumed to be those given above as part of the reaction formula definition If the reaction is a three-body reaction as well. / M / A / α1 / B / α2 / … Rules: • • Keyword M must be enclosed by two ‘/’ characters and is not case sensitive A. i.e. … are the corresponding efficiency factors. i. temperature exponent and activation energy values for the high pressure limit are assumed to be those given above as part of the reaction formula definition Keyword TROE must be enclosed by two ‘/’ characters and is not case sensitive a. add a line starting with keywords EBU after the reaction formula. d and e are the corresponding SRI parameters and are separated from each other by at least one blank space.e. If B ebu is not zero. a new line is added starting with ‘ / M / ’ and the third body efficiency factors. / EBU / A ebu B ebu IOP f i Rules: • • Keyword EBU must be enclosed by two ‘/’ characters and is not case sensitive A ebu and B ebu are constansts appearing in the standard eddy break-up model. see equation (10-8). c and d are the corresponding Troe parameters (d is optional) If the reaction is a three-body reaction as well. after the reaction formula. reaction rate determined by equation (10-8) 8-13 Version 4. c. i. b. i. / LOW / A L β L E L / SRI / a b c d e Rules: • • The definition of keyword LOW is the same as above The pre-exponential factor. temperature exponent and activation energy values for the high pressure limit are assumed to be those given above as part of the reaction formula definition Keyword SRI must be enclosed by two ‘/’ characters and is not case sensitive a. the product will be included in the reaction rate calculation. add two lines starting with the keywords LOW and SRI. IOP is an integer determining which EBU model is being used: IOP = 1 : Standard EBU model. a new line is added starting with ‘ / M / ’ and the third body efficiency factors.e.02 . • • • The Eddy Break-up reaction To define an eddy break-up reaction in turbulent combustion. respectively.Chapter 8 CHEMICAL REACTION AND COMBUSTION Complex Chemistry Models / TROE / a b c d Rules: • • The definition of keyword LOW is the same as above The pre-exponential factor. If the reaction is a three-body reaction as well. b. • • • The SRI fall-off reaction To define a SRI fall-off reaction. 1600 6964 0. 8-14 Version 4. H + O2 = OH + O O + O = O2 2. “Ignition” in the Methodology volume) • In an eddy break-up reaction defined as A1 + A2 + … → B1 + B2 + … species A1 will be treated as the fuel. 0. the corresponding pre-exponential factor. The Reacting Flow sub-folder will appear in the NavCenter tree.7830 74. respectively.80E10 0.CHEMICAL REACTION AND COMBUSTION Setting Up Chemical Reaction Schemes Chapter 8 IOP = 2 : Combined time scale model.40/ H2O/5. 1. A2 as the oxidizer and B1 as the product.16 / TROE / 0.0/ / LOW / 1.0 16795 0 19208 2385 3000 0.Y P . 6.02 . /M / CO + O = CO2 1. reaction rate determined by equation (10-15) IOP = 3 : Hybrid kinetic/EBU model.0 2941.667 235.00E12 0.3E25 –3.Y O .0/ H2O/6. / EBU / 4.0E14 0.62E16 –0.0/ CH4/2. temperature exponent and activation energy are defined as usual. reaction rate determined by equation (10-11) For IOP = 2 or 3. The mass fractions corresponding to these species are denoted in equation (10-8) as Y F . Click Apply.020E14 0.0 740 4536.0 / TROE / CH4 + 2O2 = CO2 + 2H2O 0.60/ HCO = CO 1. 0. 0.84 / M / H2/2.150 / M / H2/2. / LOW / H + CH2 = CH3 6.5/ CO2/2. 1 CH + N2 = HCNN 3.2 + H 5. 0.76 / LOW / .1E12 0.0 ! modified Setting Up Chemical Reaction Schemes Step 1 Go to the “Select Analysis Features” panel and choose option Chemical Reaction from the Reacting Flow menu. Table 8-2 2. An example reaction mechanism file is shown in Table 8-2. nested inside folder Thermophysical Models and Properties.0 2117.75/ CO2/3. The eddy break-up reaction is also assumed to be irreversible. f i is optional and represents the burnt fuel mass fraction used in ignition modelling (see Chapter 10.24E4 0.00/ CO/1.04E26 –2.0/ CO/1.40/ CH4/2. It is also important that definition of all domain (material) properties via panel “Molecular Properties” has already been completed before any scalar properties are defined. You should therefore go to the “Molecular Properties (Scalar)” panel to specify the missing properties before proceeding further. choose an ignition model or ignition start-up scheme.02 8-15 . • The parameters of a reaction can be redefined at any time by selecting its parent scheme via the Chemical Scheme # scroll bar and then making the necessary changes. open panel “Scheme Definition” and select a free scheme number using the Chemical Scheme # scroll bar at the bottom of the panel. use the on-line help provided to assist you in specifying the relevant chemical reaction definitions. Partially Premixed. Note that: • If a species cannot be mapped to a material in a database. You must then: Specify the basic reaction type (Unpremixed/Diffusion. • For some models. pro-STAR associates all chemical species defined in this panel with additional scalar variables of the same name and also does a stoichiometric check for every reaction. go to panel “Emission” and activate the built-in pollutant emission models for NOx and/or soot • Version 4. Step 5 In the “Ignition” panel. you will also need to specify the form of their Implementation or the method of calculating the Unburnt Gas Temperature. Step 3 Go to the Chemical Reactions sub-folder.Chapter 8 CHEMICAL REACTION AND COMBUSTION Setting Up Chemical Reaction Schemes Step 2 Open the Reacting Flow sub-folder to display a second sub-folder called Chemical Reactions. depending on the chemical scheme type defined in Step 3 Step 6 If required. Premixed. a warning is displayed in the Output window and a fresh scalar of that name (but with undefined properties) is created and added to the scalars list. This contains all panels needed to fully define a chemical reaction scheme. Step 4 In the “Reaction System” panel. • If the mass fraction of a non-reacting species is to be included in the calculations. or Heterogeneous/Surface) by choosing an option from the Reaction Type menu • Select the most appropriate reaction model for your problem from the Reaction Model menu. control settings and model parameters. The menu options depend on the reaction type specified above. assign a scalar variable to the species via the “Molecular Properties (Scalar)” panel and put it at the end of the existing scalars list. The required scalars and their properties are retrieved from pro-STAR’s built-in database. as explained in the “Scheme Definition” Help topic. 0 — 1. by an internal algebraic equation. in effect. the “Additional Scalars” panel (Equation Behaviour sub-folder) enables you. Step 9 Go back to Step 3 and repeat the above process until all schemes have been defined.CHEMICAL REACTION AND COMBUSTION Setting Up Chemical Reaction Schemes Chapter 8 Step 7 Some schemes allow the inclusion of knock modelling as part of the overall chemical reaction simulation process. especially if Step 4 above found missing scalars that were subsequently defined manually. using only the eddy break-up model for all reactions.02 . Step 8 If the Coupled Complex Chemistry model is in use. The steady-state under-relaxation factors for temperature T and all scalar variables representing transported mass fraction. In multi-domain problems where each domain has a different scalar composition. You are strongly recommended to perform stoichiometric checks for every reaction. click the Check Stoichiometry button in the Reaction System tab when you have finished setting up the model and before writing data to the problem (. To do this. Note that it is not necessary to assign every available scheme to one of the domains. e. 3. 2. go to panel “Solution Controls” to select the appropriate solution method controls and to perform the necessary species-to-scalar mapping.prob) file. 89 and 90 when running combustion cases. For steady-state problems involving reactions that use a hybrid model. Thus. numerical under.and over-shoots that can destabilize the solution process may be avoided Constant 89 can be assigned to the minimum allowable temperature calculated by STAR Constant 90 can be assigned to the maximum allowable temperature • • Useful general points for local source and regress variable schemes 1. The recommended range is 0. It is strongly recommended to make use of pro-STAR Constants 64. etc. The chemical kinetic model should then be employed by selecting the Combined/User option and the analysis continued using the hybrid model until the final solution is obtained. by performing separate analyses for each combination.g. should be identical. This allows you to define redundant schemes and then experiment with different schemes for the same domain. Step 10 Assign a reaction scheme to every fluid domain in your model using the “Scheme Association” panel. Note that this factor has no effect for scalars calculated by other means.0. The residual error tolerance for temperature and all scalar variables can be 8-16 Version 4. experience so far has shown that the best practice is to obtain a converged solution first.7. mixture fraction. Parameters for this model may be specified in panel “Knock”. Their effect is as follows: • Setting Constant 64 = 2 will constrain calculated values for all active scalar mass fractions to the range 0. 4. to select which scalars exist in what domain.3 to 0. These must also be given names that are different from those of the parent species participating in the chemical reaction and make sure that their properties (as defined in the “Molecular Properties (Scalar)” panel) are correct. Therefore: (a) If N2 does not appear in a reaction definition. Version 4. 12.01 to 0.001. By default. 11. 10. 7. individual reactions in multi-step reaction systems can be turned on or off at appropriate points in the simulation. If a regress variable is employed by a combustion model. its initial value must be set to 1 for correct model operation. The value of the N2 mass fraction returned by STAR is such as to make the mass fractions at every cell sum to 1. If the same reaction appears in more than one scheme. it is convenient to include N2 as a separate scalar to represent the background material.0 (b) If N2 is present in a reaction definition. its physical properties are those for nitrogen and the solution method is set to Internal (see panel “Additional Scalars”). user input can be reduced by employing command RSTATUS to copy the reaction definition from a previous scheme to the current one. 6. This may be done by selecting Off in the Status pop-up menu corresponding to the reaction concerned. STAR will then be able to distinguish between species representing products of the chemical reactions and the ones coming from the EGR stream.Chapter 8 CHEMICAL REACTION AND COMBUSTION Setting Up Chemical Reaction Schemes 5. the recirculated gases must be explicitly defined as active transported scalars within STAR Guide’s “Additional Scalars” folder. you are recommended to choose option Polynomial in the “Specific Heat” pop-up menu. particularly in the case of turbulent combustion. This will increase the number of sweeps per PISO iteration but will improve the accuracy. 9. pro-STAR will automatically set up an extra active scalar called N2. The turbulent Prandtl and Schmidt numbers for all scalar variables should be identical. N2 will be set up like any other scalar and its solution method will be set to Transport. When defining domain material properties via the “Molecular Properties” panel in STAR-GUIde. Chemical reactions (especially those for combustion) commonly take place in a domain where air is the background material. If you are modelling an EGR system. 2]. set via the “Diffusivity” panel in STAR-GUIde. 13. the Constant option is recommended for maximum efficiency.02 8-17 . A polynomial variation for molecular viscosity and thermal conductivity can be specified in the same way. 8. If modelling considerations demand it. tightened from the default value of 0. For mass diffusivity. Given that the nitrogen component is often chemically inert and therefore does not appear in a chemical reaction equation. This will load suitable polynomials from the CHEMKIN or CEC thermodynamic databases [1. the value of mixture fraction is known and remains constant throughout the analysis. For premixed flames. Complex chemistry models must be run in double precision. You must therefore ensure that the regress variable scalar in your model is initialised properly before proceeding with the simulation. Note that. f s and g ξ become scalar numbers 1 to 4. Their names will appear in the Reactant Parameters list.02 . If a reaction constituent only occurs on the right-hand side of all reaction equations. 2. point no. In multiple reaction schemes. if you wish this constituent to be a reactant (see. 3. Therefore. beginning with scalar 8-18 Version 4. respectively. For the multiple-fuel model. 4. on page 8-2). In single-fuel PPDF models.CHEMICAL REACTION AND COMBUSTION Setting Up Chemical Reaction Schemes Chapter 8 Chemical Reaction Conventions The following conventions should be observed when typing reaction definitions in the “Reaction System” panel: 1. once the reaction details are confirmed. . the normal rule for what may appear as a product is as follows: (a) Reaction 1 is allowed to produce leading reactants 2 to 30 as products (b) Reaction 2 is allowed to produce leading reactants 3 to 30 as products (c) Reaction 3 is allowed to produce leading reactant 4 to 30 as products . 6. the quantities f and g f are automatically assigned by STAR-CD as scalar numbers 1 and 2. . Enter the ‘→’ symbol as two consecutive characters ‘->’ 2. once the reaction details are confirmed. g f . Its name will appear in the Leading Reactants list at the bottom of the panel. Specify the leading reactant as the first chemical substance on the left-hand side of the reaction equation. the two equations in the following scheme CH 4 + 1. 4. point no. However. The system in this example also includes an influx of H 2 O from an external source so that both O 2 and H 2 O are reactants in this case. it will be assumed to be a product and its name will appear in the Products list. (d) Reaction 29 is allowed to produce leading reactant 30 as a product (e) Reaction 30 is not allowed to produce any leading reactants For example.5 O2 → CO + 2H 2 O [ r ] CO + 0. 5. the quantities f p . the symbol [R] needs to be entered after the latter’s name. STAR will still allow one reaction only to create a product that has already been defined as the leading reactant of a previous reaction.5 O 2 → CO 2 should be defined in the order shown above and not the other way round in order to satisfy this rule. Useful points for PPDF schemes 1. type the symbol [R] immediately after its name. Any additional variables are assigned to further scalars. 5 above notwithstanding. for example. Specify up to three ordinary reactants taking part in the reaction(s). This can be confirmed by displaying a STAR-GUIde panel that contains a Scalar list (for example. However.Chapter 8 CHEMICAL REACTION AND COMBUSTION Setting Up Chemical Reaction Schemes number 3 (single-fuel) or 5 (multiple-fuel). 4. These are illustrated in the Figure below: Version 4. However. density and all other variables are calculated internally. (c) Polynomial coefficients should be supplied in terms of molar fractions (kmol/kmol). scalar concentrations for initial and boundary conditions should be specified as mass fractions. Thus the density setting in the “Molecular Properties” panel is automatically changed to read PPDF. if any additional non-reacting scalars are defined (see “Setting Up Chemical Reaction Schemes”. However.P) option is used for density (see topic “Density”) (d) The Polynomial option is used for specific heat (see topic “Specific Heat”) (e) The scalar species concentrations are specified in terms of mass fractions 5.02 8-19 . check the information displayed by the STAR-GUIde interface to ensure that: (a) Option Active is selected from the Influence pop-up menu for all chemical species (“Molecular Properties (Scalar)” panel in folder Additional Scalars) (b) Option Chemico-Thermal is selected from the Enthalpy pop-up menu (“Thermal Models” panel in folder Liquids and Gases) (c) The Ideal-f(T. (b) pro-STAR provides a reminder that density is no longer calculated by one of the normal options. Temperature. STAR will output the calculated species concentrations in terms of mass fractions. Step 4) these are solved in the normal way. a number of control parameters should be specified. the output will be in terms of species mole fractions. if all species molecular weights are assigned the same value. (d) If the molecular weights of all scalar species are correctly specified. If the PDF is to be calculated by numerical integration. In adiabatic PPDF applications: (a) Remember that only the quantities given in item 1 above are calculated from transport equations. In non-adiabatic PPDF applications. 3. “Initialisation” in the Additional Scalars folder). CHEMICAL REACTION AND COMBUSTION Setting Up Chemical Reaction Schemes Chapter 8 φ MF ×× × N1 0 N2 fs } Ni Ni+1 1 NF f Figure 8-1 Control parameters for PDF integration The quantities shown in Figure 8-1 are defined as follows: (a) f s — stoichiometric mass fraction (b) N F — mixture fraction points. This is the total number of locations where chemical equilibrium calculations are performed. (c) MF — multiplying factor. This is the number of points added between any two adjacent points, such as N i and N i + 1 . These extra points are used for improving the resolution of the calculation and their values are extrapolated from those at N i and N i + 1 . The total number of points Nt used in the integration is given by (8-2) N t = ( MF + 1 ) × ( N F – 1 ) + 1 . (d) P F — integration partition. This parameter represents the percentage of points used to resolve the region between 0 and f s in the mixture fraction space, i.e. the number of points in this region is given by ( P F ⁄ 100 ) N t 6. When using the laminar flamelet model, the following points should be borne in mind: (a) Each flamelet library refers to a different strain rate. A typical example might be to have 6 flamelet libraries at strain rates of 0, 25, 50, 200, 400 and 1000 s-1. (b) Calculating flamelet libraries may be very time consuming. Therefore, when creating a new library, you should consider restarting the calculation from the nearest available strain rate wherever possible. However, if the difference in strain rate is quite large and convergence becomes difficult, it will be necessary to specify a new set of initial conditions and start again. (c) STAR-CD provides an option for either specifying the inlet strain rate or 8-20 Version 4.02 Chapter 8 CHEMICAL REACTION AND COMBUSTION Setting Up Chemical Reaction Schemes calculating it via a built-in code. For simplified reaction mechanisms, try the first alternative combined with the restart option from a previously converged strain rate. For more complex mechanisms, you may want to try the second alternative, check what strain rate the code calculates, and then change the initial conditions accordingly. When the initial conditions are sufficiently close to the desired strain rate, you may be able to select the first alternative with a restart option to achieve a solution. (d) The results of each flamelet library calculation are printed out in a separate output panel. You should always inspect that panel to ensure the displayed values are reasonable. (e) If your problem setup contains multiple reaction scheme definitions, any laminar flamelet model(s) should appear at the top of the reaction scheme list. Useful points for complex chemistry models 1. The distinction between premixed, partially premixed and unpremixed combustion made in the pro-STAR GUI is irrelevant for complex chemistry models, since transport equations are solved for all species (or one of them is calculated as 1 – Σ Y i ). Hence, this model is available for all the above reaction types. 2. The calculation of reaction rates can be very time-consuming. Users may therefore specify, via Constant 173, a temperature limit below which reaction rates will not be calculated. The default value of this limit is 300 K but may be re-set as necessary. 3. The steady-state complex chemistry solver employs an internal sub-timestep whose default value is 10–5. Users may change this value via Constant 154. Normally, a very small sub-timestep value will result in the calculation of large reaction rates, which could in turn make the solution of the steady-state transport equations unstable. On the other hand, if the value is too large, the chemistry solver will become very time-consuming. 4. For very stiff problems, the maximum number of sub-timesteps may need to be increased beyond its default value, currently set at 500. This is done via Constant 192. Users can also change the chemistry solver’s relative and absolute convergence tolerance via Constants 123 and 124, respectively. The default values for these are set at 10–4 and 10–10, respectively. 5. There is a balance between robustness and convergence rate. The latter may be increased by higher values of the species under-relaxation factor, but users should be careful that the stability of the solution is not sacrificed at the same time. 6. For steady-state cases, it is recommended that the initial species distribution should correspond to a non-combustible mixture, such as air. Useful points for ignition models 1. Shell and 4-step ignition models: Option Use Heat of Reaction in the “Reaction System” STAR GUIde panel is valid only when the pro-STAR-defined specific heat polynomial coefficients are used. When the reaction is exothermic, the heat of reaction value is negative. For an Version 4.02 8-21 CHEMICAL REACTION AND COMBUSTION Setting Up Advanced I.C. Engine Models Chapter 8 endothermic reaction, the value is positive. 2. CFM ignition model: In problems where only a part of the solution domain is being simulated, you need to specify (via Constant 142) a geometrical factor whose value is the fraction of the flame kernel area in the partial (simulation) domain relative to the entire domain. For example, for a wedge-shaped solution domain in a cylindrical system and with the ignition point lying on the axis, this value should be ∆θ ⁄ 360 , where ∆θ is the angular extent of the wedge. The default value of the above factor is 1. Setting Up Advanced I.C. Engine Models The notes below describe the set up of combustion simulations that employ the CFM, ECFM, ECFM-3Z or Level Set models. Note that: • • The GUI facilities presented are available only when running the Auto Mesh version of pro-STAR (prostar -amm). Use of ECFM, ECFM-3Z and their attendant ignition models requires a special licence obtainable from CD-adapco. Note also that if you are resuming from an .mdl file in which a combustion model has been defined, it is important to delete this model, its submodels (such as NOx, Soot and Knock) and the associated scalars before selecting an alternative model. This requires issuing the following pro-STAR commands (or performing the equivalent GUI operations): SCDEL,ALL — delete all scalars SOOT,n,OFF — turn off soot modelling, where n stands for every curently-defined chemical scheme number NOX,n,OFF — turn off Nox modelling KNOCK,n,OFF — turn off knock modelling CRDEL,ALL — delete all chemical reaction schemes CHSCHEME,m,NONE — remove chemical scheme associations with STAR domains (streams), where m stands for every currently-defined domain CHER,OFF — turn off chemical reaction calculations To set up a case: Step 1 In the Select Analysis Features panel, select all general features required for an engine combustion simulation (these parameters will be selected in advance if the es-ice engine simulation expert system is used): • Time Domain > Transient (select option Angle and enter values for RPM and Initial Position) • Reacting Flow > Chemical Reaction • Multi-Phase Treatment > Lagrangian Multi-phase (if modelling sprays) Step 2 Select folder Thermophysical Models and Properties > Liquid and Gases and then enter appropriate values in the following panels: Version 4.02 8-22 Chapter 8 CHEMICAL REACTION AND COMBUSTION Setting Up Advanced I.C. Engine Models Molecular Properties Turbulence Models Thermal Models (select Temperature Calculation On and then choose options Conservation > Static Enthalpy and Enthalpy > Thermal) • Initialization • Monitoring and Reference Data • Buoyancy (where applicable) Step 3 At this stage, the special IC set-up panel can be used, accessed by selecting Advanced > IC Setup from pro-STAR’s main menu. The panel shown below will then pop up: • • • The panel will initially display the Analysis setup sub-panel. Check that the Combustion option is selected and then choose the type of combustion model required from the drop-down menu underneath. • Fuel parameters: Select the desired fuel from the second drop-down menu. Depending on the model type, i.e. spark or compression, the panel will display a default octane or cetane number in the text box on the right. You should replace this with an appropriate value if necessary. The corresponding chemical reaction formula will also be displayed below the fuel name. Step 4 Click the Combustion tab button on the left to display the Combustion sub-panel. Its contents depend on the combustion model selected, as described below. • Version 4.02 8-23 CHEMICAL REACTION AND COMBUSTION Setting Up Advanced I.C. Engine Models Chapter 8 Coherent Flame model (CFM) The chemical reaction for the chosen fuel is displayed at the top. • Modelling parameters — enter values for coefficients α and β to be used in the source term of the Σ equation (see equation (11-10) in the Methodology volume). Ignition parameters: (a) In the Spark time box, input the time (in degrees crank angle or in seconds) at which the spark is to be discharged (b) Enter the ignition Location in terms of X, Y, Z coordinates relative to 8-24 Version 4.02 • Chapter 8 CHEMICAL REACTION AND COMBUSTION Setting Up Advanced I.C. Engine Models coordinate system no. 1 (in model units) (c) In the Delay box, enter the time delay (or transition time t1 , see Chapter 11, “Ignition treatment for the CFM-ITNFS model” in the Methodology volume) (d) In the Kernel diameter box, enter the appropriate value in mm • • • Enter the Mixture fraction for the premixed air-fuel mixture Specify whether exhaust gas recirculation (EGR) should be On or Off Specify whether emissions (NOx) and/or Knock is to be modelled by selecting On or Off from their respective drop-down menus. Apart from the above input, the panel will also execute commands to effect the following changes (which will overwrite any property settings specified previously in pro-STAR’s Molecular Properties panel): • • • Set up appropriate property definitions for material #1 and change the molecular viscosity setting to MultiComponent Define the specific heat setting of the background fluid as Polynomial Create chemical species scalars and assign appropriate physical properties to them, imported from the built-in property database props.dbs Note that there is an alternative method of setting up a CFM model using pro-STAR’s Chemical Reactions panels in STAR GUIde. The main difference between the two is that • • pro-STAR specifies the ignition location in terms of the centroid of an ‘ignition cell’ the IC Setup panel specifies the location in terms of its X, Y, Z coordinates and passes them on to STAR via an Extended Data segment delimited by the keywords BEGIN SPARK_DATA and END SPARK_DATA and appended to the .prob file. It is most important that the two approaches should not be mixed. Version 4.02 8-25 CHEMICAL REACTION AND COMBUSTION Setting Up Advanced I.C. Engine Models Chapter 8 Extended Coherent Flame model (ECFM) The chemical reaction for the chosen fuel is displayed at the top. • Modelling parameters — enter values for coefficients α and β to be used in the source term of the σ equation (see equation (11-90) in the Methodology volume). The PSDF Moments soot model may be used by selecting On from the Mauss Soot Model drop-down menu (see “Soot Modelling” on page 8-39) Version 4.02 • 8-26 Chapter 8 CHEMICAL REACTION AND COMBUSTION Setting Up Advanced I.C. Engine Models • Ignition parameters — there are two ignition model choices: (a) Standard: i) In the Spark time box, enter the time (in degrees crank angle or in seconds) at which the spark is to be discharged ii) Enter the ignition Location in terms of X, Y, Z coordinates relative to coordinate system no. 1 (in model units) (a) Aktim — see “The Arc and Kernel Tracking ignition model (AKTIM)” on page 8-33 • Enter a Sector angle value if you want to perform a “Sector Mesh” analysis. The panel also executes additional commands to effect the following changes: • • Turn on the Transient setting and associate the ECFM chemical scheme with material #1 Define 17 scalars and their material properties Version 4.02 8-27 • Modelling parameters — enter values for coefficients α and β to be used in the source term of the σ equation (see equation (11-90) in the Methodology volume).02 • 8-28 .CHEMICAL REACTION AND COMBUSTION Setting Up Advanced I.C. Select the Multiple Cycles option if you wish to run a simulation over multiple engine cycles Version 4. Engine Models Chapter 8 Extended Coherent Flame model 3Z (ECFM-3Z) — spark ignition The chemical reaction for the chosen fuel is displayed at the top. Coordinates for each ignition location can be entered by selecting the particular location from the drop-down menu.Chapter 8 CHEMICAL REACTION AND COMBUSTION Setting Up Advanced I. Ignition parameters — there are two ignition model choices: (a) Standard: i) In the Spark time box.C. • Modelling parameters — enter values for coefficients α and β to be used in the source term of the σ equation (see equation (11-90) in the Methodology volume). 1 (in model units) (b) Aktim — see “The Arc and Kernel Tracking ignition model (AKTIM)” on page 8-33 • • • Multiple ignition locations — the number of locations can be increased/decreased by clicking the up/down # location arrows. Select the Multiple Cycles option if you wish to run a simulation over multiple engine cycles The PSDF Moments soot model may be used by selecting On from the Mauss Soot Model drop-down menu (see “Soot Modelling” on page 8-39) 8-29 • • Version 4. in degrees crank angle or seconds.02 . Extended Coherent Flame model 3Z (ECFM-3Z) — compression ignition The chemical reaction for the chosen fuel is displayed at the top. the panel defines 25 appropriate scalars and their material properties. Specify whether Knock is to be modelled by selecting On or Off from the drop-down menu Enter a Sector angle value if you want to perform a “Sector Mesh” analysis. Y. Z coordinates relative to coordinate system no. The user should set this time equal to the time when fuel injection starts. enter the time (in degrees crank angle or in seconds) at which the spark is to be discharged ii) Enter the ignition Location in terms of X. Engine Models • • • The PSDF Moments soot model may be used by selecting On from the Mauss Soot Model drop-down menu (see “Soot Modelling” on page 8-39) Parameter Start of ECFM-3Z is the time at which fuel / air mixing and combustion will start to be calculated. In addition. except for scalar RVB (the progress variable ‘c’) which should be Internal. users can supply their own fuel definition by selecting option User Defined from the fuel selection drop-down menu and then specifying the number of C and H atoms.e.prob file when the later is saved at the end of the current pro-STAR session. H2 and SOOT are turned off. along with O2UM and FUM.02 . 8-30 Version 4. If ECFM models are applied in materials other than no. NO. Although the list of fuels for use in these models is limited. SOOT.CHEMICAL REACTION AND COMBUSTION Setting Up Advanced I. All ECFM models must be run in double precision. 5. TSOOT) must be set equal to the corresponding initial mass fractions of species Fuel and O2 plus. in degrees crank angle or seconds.C. 4. 9. the system is always “mixed”). H2. Engine Models Chapter 8 • • Parameter Start of ECFM-3Z is the time at which fuel / air mixing and combustion will start to be calculated. Additional scalars may be added but they must be Inactive. The specific heat ‘cp’ should be changed accordingly. 1. The segment is appended to the end of the . species CO. H. O. 8. This segment is created automatically and may be inspected by selecting Utilities > Extended Data from the main pro-STAR window’s menu bar but the user does not need to add any further information to it. The ECFM model is currently emulated by the ECFM-3Z model.0 (i. Useful points for ECFM models 1. ECFM models cannot be used in conjunction with the k-ω or the Spalart-Allmaras turbulence models. TO2) plus any other applicable tracers (TCO. 6. TNO. For unburnt gases. TH2. and the corresponding mass fractions are set to 0. make sure that the solution method for scalars in these materials is the same as for material 1. the initial mass fractions of fuel and oxygen tracers (TF. Model parameters should be specified via the panels described in this document. The correct setting is Transport. Users should not attempt to supply any parameters via the standard pro-STAR STAR GUIde panels. 7. 10. OH cannot be present as part of EGR gases. 2. Comparisons with results from earlier STAR-CD implementations will show slightly differences as different sub-models for the post-flame regime are used in the current version. 3. There is an additional option to turn On the Tabulated Double-Delay Autoignition Model (see “The Double-Delay autoignition model” on page 8-37). The user should set this time equal to the time when fuel injection starts. if applicable. The information entered in the ECFM and ECFM-3Z panels is passed on to STAR via an Extended Data segment delimited by the keywords BEGIN ECFM_DATA and END ECFM_DATA. It is important to remember that species N. CO. Tracers for species NO. This segment is created automatically and may be inspected by selecting Utilities > Extended Data from the main pro-STAR window’s menu bar.prob file when the later is saved at the end of the current pro-STAR session. as described in Chapter 9 of the Supplementary Notes volume. Y. Engine Models Level Set model The chemical reaction for the chosen fuel is displayed at the top. The user does not normally need to add any further information to it unless advanced features of the model need to be implemented. Data for each ignition kernel can be entered by selecting the particular location from the drop-down menu.02 8-31 . • • • Re-initialization method — select an option from the adjacent pop-up menu (see Chapter 9. enter the time (in degrees crank angle or in seconds) at which the spark is to be discharged (b) Enter the ignition kernel Location in terms of X. The information entered in the Level Set panel is passed on to STAR via an Extended Data segment delimited by the keywords BEGIN LEVELSETDATA and END LEVELSETDATA. “Re-initialisation” in the Supplementary Notes volume) Select the Multiple Cycles option if you wish to run a simulation over multiple engine cycles Ignition parameters (a) In the Spark time box.Chapter 8 CHEMICAL REACTION AND COMBUSTION Setting Up Advanced I.C. Z coordinates relative to coordinate system no. 1 (in model units) and ignition kernel Radius (in metres) (c) Enter the ignition Duration (in degrees crank angle or in seconds) • Multiple ignition kernel locations — the number of locations can be increased/decreased by clicking the up/down # location arrows. Version 4. The Extended Data segment is appended to the end of the . Engine Models Chapter 8 Step 5 Click the Write data tab button on the left to display the Write data sub-panel. Only those scalars included in a list should be initialised.02 For ECFM-3Z: (a) (b) (c) (d) (e) 8-32 . all others should have 0 as their initial value.CHEMICAL REACTION AND COMBUSTION Setting Up Advanced I. Write Data sub-panel In this panel: • Click Save parameters to save the combustion parameters to a file called star.mdl) file and close the panel Click Close to close the panel without writing anything to the . shown below.mdl file. The file name can be changed if necessary.mdl file • • Step 6 Initialize certain scalars.ics. as shown below. This file is important as it contains combustion data and should be kept together with the . Click Write and close to write the problem settings to a model (. • For ECFM: (a) (b) (c) (d) (e) (f) (g) • Fuel → set the fuel initial mass fraction O2 → set the O2 initial mass fraction CO2 → set the CO2 initial mass fraction H2O → set the H2O initial mass fraction N2 → set the N2 initial mass fraction TF → set the unburnt fuel initial mass fraction TO2 → set the unburnt O2 initial mass fraction Fuel → set the fuel initial mass fraction O2 → set the O2 initial mass fraction CO2 → set the CO2 initial mass fraction H2O → set the H2O initial mass fraction N2 → set the N2 initial mass fraction Version 4.C. Otherwise.Chapter 8 CHEMICAL REACTION AND COMBUSTION Setting Up Advanced I. • • • Version 4. Engine Models (f) (g) (h) (i) (j) (k) (l) TF → set the unburnt fuel initial mass fraction TO2 → set the unburnt O2 initial mass fraction TCO → set the unburnt CO initial mass fraction TH2 → set the unburnt H2 initial mass fraction TNO → set the unburnt NO initial mass fraction TSOOT → set the unburnt soot initial mass fraction FUM → set the initial mass fraction of the Unmixed Fuel (default value is 0) (m) O2UM → set the initial mass fraction of the Unmixed Oxygen Step 7 Define the time step size and any load steps in the appropriate transient settings panel (where applicable). as follows: • • • • • Select the required ECFM model Choose option Aktim from the Ignition menu In the Spark time box. Coordinates for each ignition location can be entered by selecting the particular location from the drop-down menu. select Area and temperature from the Electrode Model menu and input the surface area and temperature of the anode and cathode.C. Z coordinates relative to coordinate system no. The two alternatives are illustrated below. Specify the Diameter of the cathode and anode electrodes Input values for parameters E 2 ( t SI ) . Y. 1 (in model units) If the electrodes are represented as distinct entities in the mesh. R in the Secondary Circuit section of the panel Multiple ignition locations — the number of locations can be increased/ decreased by clicking the up/down # location arrows. enter the time (in degrees crank angle or in seconds) at which the spark is to be discharged Enter the ignition Location in terms of X. select option Regions from the Electrode Model menu and input the boundary region numbers corresponding to the anode and cathode. The Arc and Kernel Tracking ignition model (AKTIM) AKTIM may be used only with one of the ECFM options.02 8-33 . L . Engine Models Chapter 8 8-34 Version 4.CHEMICAL REACTION AND COMBUSTION Setting Up Advanced I.02 .C. For such problems: • Version 4. Engine Models Useful points for the AKTIM model Use of Extended Data The information contained in the above panels is passed on to STAR via the ECFM Extended Data segment (see “Useful points for ECFM models” on page 8-30).C. The contents of this segment do not need to be altered by the user except in the case of two-dimensional (x-y) problems.02 Select Utilities > Extended Data from the main pro-STAR window’s menu 8-35 .Chapter 8 CHEMICAL REACTION AND COMBUSTION Setting Up Advanced I. Post and track data Two new files are written by STAR when AKTIM is in use: 1. Mesh quality It is important to use good quality meshes when the electrodes are resolved. Temperature.POST. progress variable. the track file for spark particles 2.strk and . In addition. from the Fill Color menu in STAR GUIde’s Plot Droplets/Particle Tracks panel No other options in the Fill Color menu are supported • There are no files equivalent to .ktrk files can be used in the same way as .ccm file contains all solution data and can be used to plot spark particles and flame kernel particles. the wrinkling factor.CHEMICAL REACTION AND COMBUSTION Setting Up Advanced I. Enter a new line containing the keyword TWODS anywhere within the segment (typically at the end) Save and then Close the Extended Data panel Entering the above keyword enforces the turbulent fluctuation contribution to the calculation of the flame kernels’ positions in the z-direction to be zero. spark particles will not be permitted to pass between different processor domains. the track file for flame kernel particles Track files The . This is because the source terms might be very high during the ignition process. casename. “The Particle Track File” in the Post-Processing User Guide).02 .strk.trk files for droplets (see Chapter 7.pstt or . 8-36 Version 4. mass and burnt gas mass in the flame kernel particle can be plotted by selecting Diameter. Mass and Count. Note that: • This action will erase all current droplet track data • Only option Constant is supported in the Droplet Radius menu • Only option Color is supported in the Fill Color menu Post files The . They can be loaded via the Plot Droplets/Particle Tracks panel by choosing option Track File in the Load Droplet Data section and then specifying the appropriate file name and extension.C. Engine Models Chapter 8 • • bar to display the current ECFM_DATA segment in the Extended Data panel.ccm file is loaded. casename. localized and big numerical errors due to poor quality meshes may lead to wrong results.ktrk. instabilities and/or divergences. respectively. HPC issues For HPC calculations. Note that: • After the . the electrodes must be meshed or specified in only one processor domain.POST.ccm_timestep for the spark and flame kernel particles. These can be loaded into pro-STAR via command GETD.FLAME for flame kernel particles.SPARK for spark particles or GETD. Thus. nE.. By default... X.. The primary ignition delay time tdelay1 2. STAR requires three types of data for this model: 1. Program Example_UserData c c nT. tdelay1. secondary delay and burnt fuel mass fraction.p(nP) are the nP pressure (bars) points in the table in ascending order. tdelay2.dat. The burnt fuel mass fraction ffrac Each of the above is tabulated at nT values of temperature T. delay2. compression and then turning On the Tabulated Double-Delay Autoignition Model option. Tstep are the minimum temperature and the temperature step (K) in the table. c respectively. so that c T(1)=Tmin. respectively. nP values of pressure p. as shown below.02 8-37 .C. Tstep. Scalar YIG monitors the progress of the main autoignition. a 4-dimensional array structure is employed for each data item. T(3)=T(2)+Tstep. Enter a new line containing the keyword LU2DATA in the line after LAUTO2 Save and then Close the Extended Data panel Create the three data files described above in a format suitable for STAR input. Users may also use their own data by storing them in three separate text files called delay1. The files must be placed in the case working directory. T(2)=T(1)+Tstep. Version 4. User data creation procedure The following steps are necessary to create user-generated data files: • • • • Select Utilities > Extended Data from the main pro-STAR window’s menu bar to display the current ECFM_DATA segment in the Extended Data panel. . the model uses ignition delay data read from pre-computed tables. Hence.dat and ffrac.. ffrac are user input data.Chapter 8 CHEMICAL REACTION AND COMBUSTION Setting Up Advanced I. p.. Tmin. c p(1). Engine Models The Double-Delay autoignition model This model may be employed by selecting ECFM-3Z. nP.dat for the primary delay. nE values of equivalence ratio E and nX values of residual gas mole fraction X. The Fortran program listed below shows how these files should be written. A new scalar YIG2 is created to track the primary autoignition progress. nX. E. c Tmin. The secondary ignition delay time tdelay2 3. The files are called check_data1 for the primary delay.p. tdelay2(iT. nE.iX).iE. File "ffrac.nX) Dimension ffrac(nT. c E(1).nP.ie.. STAR will also output three text files at the beginning of the simulation containing the parameters and data specified by the user.dat’) do ix=1. nX write(iunit.iE..02 .. nP.tdelay2.*) Tmin.ie. Tstep do ip=1.file=’ffrac.nX do ie=1. For verification purposes...nE do ip=1...nP do it=1.nT write(iunit.nP.file=’delay1.CHEMICAL REACTION AND COMBUSTION Setting Up Advanced I.ip.*)ffrac(it.E..nP do it=1.iX).Tstep..*) tdelay1(it.ffrac Dimension p(nP).ix) end do end do end do end do close(iunit) c c.nE do ip=1.*)tdelay2(it.E(nE) are the nE equivalence ratio points in the table in ascending order.nE.nE do ip=1.nP.nX) Dimension tdelay2(nT.dat’) write(iunit. secondary delay and burnt fuel mass fraction.ip.. STAR will abort the simulation with warning messages.iP.*) X(ix) end do do ix=1.dat" Double Precision Tmin.iP.. check_data2 for the 8-38 Version 4.nT write(iunit.ix) end do end do end do end do close(iunit) c c. tdelay1(iT. X(1).iX) are user-defined 4-dimensional arrays for the primary delay. X(nX) Dimension tdelay1(nT..nX write(iunit.dat" c open(iunit.X(nX) are the nX residual gases points in the table in ascending order.nP do it=1.file=’delay2. Engine Models c c c c c c c.ix) end do end do end do end do close(iunit) c end Chapter 8 Note that if any of the above files is not present.nE write(iunit.nT write(iunit.nX do ie=1.iE.dat’) do ix=1.*) E(ie) end do do ix=1. File "delay2.*) p(ip) end do do ie=1.nE. E(nE).nX do ie=1.ie.tdelay1..X.iP.ip.nP write(iunit. ffrac(iT.C.nX) c open(iunit.nE.. File "delay1.dat" c open(iunit.*) nT. coal). As a result. specify values for the required constants as explained in the on-line help topic for “NOx”. open the “Emission” panel and then go the “NOx” section. “NOx Formation” in the Methodology volume). If option On is selected for Thermal NOx. it is generally agreed that NOx chemistry has negligible influence and can be decoupled from the main combustion and flow field calculations. Step 3 Turn on the appropriate NOx production mechanism from the Thermal. e.02 8-39 . see equation (10-120) and (10-121). For example. by opening the “Molecular Properties (Scalar)” panel in the Additional Scalars folder and inspecting the currently defined scalars. Step 6 For steady-state problems. Step 2 In the Chemical Reactions folder of STAR GUIde.Chapter 8 CHEMICAL REACTION AND COMBUSTION NOx Modelling secondary delay and check_dataf for the burnt fuel mass fraction and are written into the working directory for sequential runs or into the first processor’s directory for HPC runs. that determine the magnitude of the contribution from each source term. The recommended procedure for performing a NOx analysis is as follows: Step 1 Set up the combustion model as usual. Select option On from the NOx Model menu to activate STAR-CD’s built-in NOx subroutines. Option User in any of these menus enables you to perform the necessary calculations via subroutine NOXUSR. their values will be used in equation (10-84) of the Methodology volume to implement the extended Zeldovich mechanism. Prompt or Fuel menus (see Chapter 10. Step 5 If your model provides for the calculation of OH and H mass fractions. Step 4 Check that pro-STAR has created an extra passive scalar variable called NO. Soot Modelling The Flamelet Library soot model is applicable only to unpremixed and partially premixed reactions and is activated via the Emission panel’s “Soot” section in STAR GUIde. The only user input required is four scaling factors. make sure that a sufficient number of iterations has been performed for the solution of NO and (if present) HCN to have converged. check that an additional passive scalar called HCN has also been created. a decrease in the value of the scaling factors for positive source Version 4. If the problem requires the prediction of fuel NOx (this is only applicable to nitrogen-containing fuels. NOx Modelling NOx concentration is usually low compared to other species in combustion systems.g. M2. The effect of EGR (if present) will be taken into account. depending on how many moments are to be solved for.C.0 and their default value is 1. 3 or 4 additional passive scalars with names M0. “The Flamelet Library method” described in Chapter 10 of the Methodology volume will be used. 2. Select a combustion model that allows Soot to be employed Select option Soot on in the Emissions panel If no moments need to be solved.02 8-40 . 3. this can shift the point of maximum soot volume fraction further downstream. A typical range for these factors is 0. Engine Models”) and is accessed via the GUI facilities presented when running the Auto Mesh version of pro-STAR (prostar -amm). These represent the quantities Mr ⁄ ρ with Mr the r-th moment and units of [mol/m3]. In diffusion flames.CHEMICAL REACTION AND COMBUSTION Soot Modelling Chapter 8 terms (surface growth and particle inception) results in slower formation of soot. The steps required for set-up in this case are as follows: 1. M1. or 4). 3. 2. The relevant panel is shown below: To use this model: • • • Select the required ECFM model Select option On from the Mauss Soot Model menu Choose the number of Moments to be solved for (0. 5 and 6 Define 2. Enter scaling factors (see “The method of moments” on page 10-29 of the Methodolgy volume for definitions) for the following quantities: (a) (b) (c) (d) Surface Growth Fragmentation Particle Inception Oxidation Rate • Use of this method with models other than ECFM is possible only within the pro-STAR environment. 4. STAR will Version 4.5 — 10. The PSDF Moments soot model may be used in conjunction with any ECFM combustion model (see “Setting Up Advanced I. If 0 is selected. bypass steps 4. M3. Step 2 Check that the temperature calculation is switched on in the “Thermal Models” panel (Liquids and Gases sub-folder) and select an appropriate turbulence model in the “Turbulence Models” panel. SootMass. N2. Mean Diameter. To reduce CPU time.spd file (see Chapter 9. Dispersion Size Distribution. N2. Select option Transport in the Analysis Control > Solution Control > Equation Behaviour > Additional Scalars panel as the method of solution for these scalars 6. the problem is re-run with coal combustion turned on. H2O in the Molecular Properties (Scalar) panel. 5. H2O. H2O arising from the EGR from the CO2.02 8-41 . If at least two moments are solved for. Then. in addition. Deactivate the SOOT scalar. Coal Combustion Modelling Coal combustion models involve two-phase flow with complex solid and gas phase chemical reactions. Note that EGR can be set up for soot cases even if no moments are solved for. Variance of the Size Distribution. as in this case the soot mass fraction is obtained from the soot PSDF moments solution 7. N2. then: (a) Define 3 new active scalars with names EGR_CO2. “Engine Combustion Data Files” in this volume). the properties in the Binary Properties panel should be the same as for scalars CO2. Number Density. EGR_H2O. EGR_N2. H2O arising from the combustion (b) Assign the same molecular properties to them as for scalars CO2. If EGR is present (up to 40% in concentration). initially the problem is run isothermally. the following (mass averaged) data will be produced at each time-step: Soot Volume. An outline of the steps involved and recommendations on model set-up at each stage of the process is given below: Stage 1 Run the model as an isothermal (non-reacting) problem and obtain a converged solution which effectively serves as an initial condition for the flow field. Version 4. it is recommended to run such a simulation as a two-stage process using the STAR GUIde system.Chapter 8 CHEMICAL REACTION AND COMBUSTION Coal Combustion Modelling identify them as the moments for the soot model. Step 1 Generate a mesh for the problem as usual and check that the steady-state analysis mode has been chosen in the “Select Analysis Features” panel. The EGR for soot calculation is not supported for PPDF models. N2. These distinguish the CO2. Thus. (c) Select option Transport in the Analysis Control > Solution Control > Equation Behaviour > Additional Scalars panel as the method of solution of the EGR scalars. Surface Density These are added after the scalar data in the . once a reasonably converged solution is obtained. Alternatively. a significantly higher amount of volatile matter can be devolved than that measured by the standard proximate analysis test. enter coal composition data and click Apply. • • Data entered in the Proximate analysis tab should be supplied on an air dried basis. go to the “Thermal Options” panel in folder Thermophysical Models and Properties and select the appropriate radiation model. including appropriate temperature distributions at inlet boundaries. This chapter also covers all other aspects of this type of model. If Cl and S need to be included in the calculations. respectively. will also open in the NavCenter tree. using the ‘Constant Rate’. The Cl and S components are then assumed to be ash. ‘1st-Order Effect’ and ‘Mixed-is-burnt’ sub-models as defaults for volatiles.CHEMICAL REACTION AND COMBUSTION Coal Combustion Modelling Chapter 8 Step 3 Define all boundaries and set up boundary conditions throughout. Details of this method are given in Chapter 3 of the Supplementary Notes volume describing coal blend modelling. At the same time. char and gas combustion. The Coal Combustion sub-folder will appear in the NavCenter tree. in the Miscellaneous tab. which is an adjustment for volatile matter. such as specifying the components and reaction rates for the different coals in the blend. Stage 2 Turn on coal combustion and generate the final solution as follows: Step 1 Go to the “Select Analysis Features” panel and choose option Coal Combustion from the Reacting Flow menu and Lagrangian Multi-Phase from the Multi-Phase Treatment menu.02 • 8-42 . Lagrangian Multi-Phase. nested inside folders Thermophysical Models and Properties > Reacting Flow. pro-STAR will set up your model automatically for this type of analysis. where C + H + O + N + Chlorine (Cl) + Sulphur (S) = 1. these components can be modelled separately via user subroutine PARUSR at a later point. as described in Chapter 7 of the CCM User Guide (see also Note 2 below). Supply the coal Q factor. Data in the Ultimate analysis tab should be supplied on a ash-free basis. This Version 4. An additional sub-folder. Step 4 Run the case until a reasonable flow field is established (see Note 1 below). Studies have shown that under certain heating conditions. The data supplied in this panel can be stored in a file called coal. Step 2 If radiation effects are to be modelled. Click Apply. you can read the coal composition from an existing file by clicking Open D/B.dbs by entering a coal name and clicking Save to D/B. Step 3 Go to the Coal Combustion sub-folder and supply or modify data in each of its panels in turn: • In the “Coal Composition” panel. choose the volatiles specific heat option (see Note 3 below). the Constant Rate scheme should be selected initially in the Volatiles tab. In the Gaseous Combustion tab. select the desired models for volatiles. The initial devolatilisation temperature should be set to that of the primary inlet flow containing the coal particles (this will help with initialising the temperature field and instigating ignition).g. The factor may be increased later on in the solution. Note that. depending on the model chosen. Also in the Miscellaneous tab. The iteration number at which particle source term averaging starts 8-43 Version 4. specify the required solution control and printout parameters. After the rest of the coal particle parameters have been set. the problem should be run using an Initial Field Restart (panel “Analysis (Re)Start”) from the isothermal solution obtained in Stage 1 and run for several hundred iterations or until a reasonably stable solution is reached. turn on the NOx generation and/or coal particle radiation options. pro-STAR will create the appropriate scalars and select the transport or internal solution method for them. The NOx model can be turned on near the end of the solution as it has only a small effect on the overall flow field. as explained in “Switches and constants for coal modelling” below. Enter the particle emissivity value. • To speed up convergence. The solution should then be re-run with a standard restart (see Notes 4 and 5 below regarding changing parameters or submodels in this panel). Char rates can be determined experimentally or taken from the literature. These require values for pre-exponential factors and activation energy that should be determined experimentally or taken from the available literature (as is the case with the default values used by STAR). Char oxidation products can be changed for specific gaseous combustion models using Constant 120. select either Mixed-is-Burnt (fast chemistry approach) or the 1-step or 2-step EBU models. It is sometimes necessary to initially reduce the under-relaxation factor of the particle source term (to as low as 0. enter the net calorific value of the fuel and the fraction of total nitrogen in the volatiles.02 . 550 K) and the model run once again using a Standard Restart until a stable solution is reached. you should already have set up your model for radiation calculations as described in Chapter 7.1) in order to achieve a stable solution. char and gas combustion. The devolatilisation temperature should then be raised to a more realistic level (e. select one of the three char models available. When this is set.Chapter 8 CHEMICAL REACTION AND COMBUSTION Coal Combustion Modelling effect is accounted for by the Q factor which is defined by (V*/VM) = Q • (8-3) where V* is the volatiles yield and VM the proximate analysis matter. • • • • In the “NOx/Radiation” panel. In the “Control/Printout” panel. • In the “Sub Models” panel. In the Char tab. as required. Finally. The Single Step or 2-Competing steps model should then be chosen. if the latter is chosen. 233.767). it may be necessary to first turn off /delete the chemical scheme definition already set-up in the “Scheme Definition” panel. Turn on the appropriate NOx models. If the coal model is turned off to run the case in non-reacting mode. thermal.g. Then go to the “Scheme Association” panel and click Apply to assign the chemical reaction schemes defined above to the current fluid domain. Step 4 Go to Chemical Reactions sub-folder and open the “Emission” panel.e. • In the Droplet Properties tab. for air YO2 = 0. Step 10 Go to the “Analysis (Re)Start” panel (Analysis Preparation/Running folder) and set up the analysis as a restart run. 8-44 Version 4. Step 9 Go to the “Scalar Boundaries” panel (Define Boundary Conditions folder) and adjust the scalar mass fractions at the inlet boundaries.02 . i. fuel and prompt NOx. Step 7 Switch off the heat and mass transfer time scale calculation by going to the “Switches and Real Constants” panel (Other Controls sub-folder) and setting constants C71 and C72 to 1. Step 11 Run the case until the solution converges or reasonably small residuals are achieved. it is advisable to run the simulation for several hundred iterations with radiation turned off before switching it back on to complete the simulation.0. Step 6 Go the “Lagrangian Multi-Phase” folder. beginning from the solution obtained in Stage 1. Step 8 Go to the “Thermal Models” panel and check that options Static Enthalpy and Chemico-Thermal have been selected for the enthalpy equation. Useful notes 1. ensure that all values of Hfg in the Component Properties list are set to 0. To avoid solution instabilities and reduce computer time in radiation cases. YN2 = 0.CHEMICAL REACTION AND COMBUSTION Coal Combustion Modelling Chapter 8 should be set to a high value to ensure a converged solution can be reached (see Note 6 below). check the settings for the Lagrangian two-phase modelling scheme and make any changes/additions necessary for defining coal particle initial positions. entrance behaviour and physical properties (panel “Droplet Physical Models and Properties”): • Turbulent dispersion can be turned on in the Global Physical Models tab to predict a realistic particle track behaviour. Step 5 Go to the “Initialisation” panel (Additional Scalars sub-folder) and set up an appropriate initial mass fraction for the carrier fluid (e. 2. This may be done by setting Constant 24 to the desired value. 7. When starting the coal combustion calculations in Stage 2. while changes in the turbulence models employed can lead to more accurate prediction of the flow aerodynamics. 5. (c) Mass Weighted considers the mixture of volatile components and calculates the overall volatile enthalpy as the sum of the products of mass fraction and enthalpy for each individual volatile component.e. Accurate modelling can be achieved through input of appropriate values for devolatilisation and char rates. you must (a) re-apply the scheme association. If you change any parameter in the “Coal Composition” panel. (c) reset Hfg = 0 for all components in the Lagrangian “Droplet Physical Models and Properties” panel. Therefore.0 — 1. it is important to include some sub-5 micron particles. and (d) define scalar boundary conditions for the inlet. This number has a default setting of 50 iterations and should be altered to a value suitable for establishing a stable flow field. the chemical reaction scheme is changed and therefore the gas combustion scheme in the “Sub Models” panel must be reset. 8. (b) CH4 assumes that all volatiles are methane. When discretising the coal particle size distribution. (b) initialise the additional scalars for the background fluid.02 Constant 24 — see Note 6 above Constant 64 = 2 — constrain active scalar values to the range 0. This enables a stable flame to be established in the immediate vicinity of the burner inlets.Chapter 8 CHEMICAL REACTION AND COMBUSTION Coal Combustion Modelling 3. 6. and to make the devolatilisation temperature equal to the particles’ initial temperature. When you re-apply the gas composition scheme. i. This is the numerical equivalent of ‘lighting up’ the combustion system in a real-life situation. In the “Coal Composition” panel (Miscellaneous tab) you have three options for setting the volatiles specific heat: (a) Coal CV (the recommended option) uses the enthalpy of volatiles calculated from the heat balance of the coal combustion for both char and volatiles. Switches and constants for coal modelling It is sometimes advisable to define some of the following pro-STAR Constants and Switches when setting up a coal model: • • • • • Version 4. H = Σ Y i hi 4. The iteration number at which to begin source term averaging should be set to a high value so as to ensure that a stable initial flow field has been achieved (and also to economize on computer time expended). Manipulating these values can increase the solution accuracy. this also resets the scalars involved. it is important to use the constant rate devolatilisation option for all particles.0 Constant 71 = 1 — deactivates the mass transfer time scale Constant 72 = 1 — deactivates the heat transfer time scale Constant 82 — specifies the coal particle emissivity in radiation problems 8-45 .   T  Y CO2 and the default values are A = 3.= A exp  --------.CHEMICAL REACTION AND COMBUSTION Coal Combustion Modelling Chapter 8 • • • • Constant 88 — specifies the maximum coal particle temperature Constant 89 — specifies the minimum carrier fluid temperature limit Constant 90 — specifies the maximum carrier fluid temperature limit Constant 120 — specifies special options for the char reaction. (b) MIX_CO2 — this is a passive scalar representing the CO2 mixture fraction and is to be solved by a transport equation. to be defined in the Additional Scalars > Molecular Properties panel: (a) MIX_CO — this is a passive scalar representing the CO mixture fraction and is to be solved by a transport equation.193 (8-4) • • • Constant 70 — used for changing the value of A in conjunction with Constant 120 Constant 74 — used for changing the value of T* in conjunction with Constant 120 Switch 71 — specifies an implicit calculation of the source terms in the particle energy equation (can improve algorithm stability) Special settings for the Mixed-is-Burnt and Eddy Break-Up models When Constant 120 is used. This is specified in panel Analysis Controls > Solution Controls > Equation Behavior > Additional Scalars panel by choosing option Internal from the Solution Method menu.26 settings (b) Constant 120 = 1 — the char reaction product is CO (c) Constant 120 = 2 — the char reaction products are CO and CO2. the product of the char reaction is CO2 Constant 120 = 1 — two extra scalars are needed. • Constant 120 = 2 — three extra scalars are needed. the following settings are also required depending on the combustion model that has been chosen: For Mixed-is-Burnt: • • Constant 120 = 0 — no extra scalars need to be defined. The latter is specified in panel Analysis Controls > Solution Controls > Equation Behavior > Additional Scalars panel by choosing option Transport from the Solution Method menu. The latter is specified 8-46 Version 4. as follows: (a) Constant 120 = 0 — use the default V3. to be defined in the Additional Scalars > Molecular Properties panel: (a) MIX_CO — this is a passive scalar representing the CO mixture fraction and is to be solved by a transport equation.02 . where Y CO –T * ----------. The latter is specified in panel Analysis Controls > Solution Controls > Equation Behavior > Additional Scalars panel by choosing option Transport from the Solution Method menu.0×108 and T* = 30. (b) CO — this is an active scalar to be solved algebraically. (c) CO — this is an active scalar to be solved algebraically.Chapter 8 CHEMICAL REACTION AND COMBUSTION Coal Combustion Modelling in panel Analysis Controls > Solution Controls > Equation Behavior > Additional Scalars panel by choosing option Transport from the Solution Method menu. For Eddy Break-Up: One-step model — Constant 120 cannot be used because the char reaction product can only be CO2 Two-step model • • Constant 120 = 0 — no extra scalars are needed. This is specified in panel Analysis Controls > Solution Controls > Equation Behavior > Additional Scalars panel by choosing option Internal from the Solution Method menu.02 8-47 . the char reaction product is CO Constant 120 = 2 — no extra scalars are needed. the char reaction products are CO and CO2 Version 4. . a number of atomisation models are employed to determine the distribution of droplet diameters and velocity directions on exit from the nozzle. Several different droplet types may coexist in your model. • User Subroutine — specify everything via a user subroutine Step 3 The second panel. set various solution control parameters (see the on-line Help text for more details). This option also allows the use of distribution functions for the droplet diameters. “Nozzle flow models” and “Atomisation models” in the Methodology volume). in which you specify the fuel mass flow rate entering the solution domain through an injection nozzle. The Lagrangian Multi-Phase folder will appear in the NavCenter tree. The same panel also defines how droplet parcel initial conditions (entrance behaviour and location) are to be specified. How this is done depends on the option chosen in Step 2. “Droplet Controls”. “Droplet Physical Models and Properties”. The present chapter contains an outline of the process to be followed when setting up a Lagrangian multi-phase simulation. mass and momentum transport mechanisms (including inter-droplet and wall collisions). Setting Up Lagrangian Multi-Phase Models Step 1 Go to panel Select Analysis Features in STAR GUIde and choose option Lagrangian Multi-Phase from the Multi-Phase Treatment menu. Step 2 In the first panel. plus droplet physical properties. containing a number of panels that are appropriate to this type of analysis. the folder will display the appropriate panel for each choice: 1. • Explicitly defined parcel injection — explicit (‘manual’) setting of all required quantities. Click Apply. so properties are specified for each individual type. The available options are: Spray injection with atomization — use one of the built-in nozzle and atomisation models (see Chapter 12. The liquid fuel is converted into droplets whose injection velocity depends on the nozzle model characteristics. Explicitly defined parcel injection — opens the following two panels: Version 4.Chapter 9 LAGRANGIAN MULTI-PHASE FLOW Setting Up Lagrangian Multi-Phase Models Chapter 9 LAGRANGIAN MULTI-PHASE FLOW The theory behind Lagrangian multi-phase problems and the manner of implementing it in STAR-CD is given in the Methodology volume. Chapter 12. In addition. Spray injection with atomization — opens a single panel. 2.02 9-1 • . including details of the user input required and important points to bear in mind when setting up problems of this kind. defines dispersed phase heat. These are especially useful in internal combustion engine studies. “Spray Injection with Atomization”. Step 4 The folder’s remaining panels relate to splitting droplets into parcels for modelling purposes and defining the latter’s entrance behaviour (initial velocities and entrance properties). LAGRANGIAN MULTI-PHASE FLOW Setting Up Lagrangian Multi-Phase Models Chapter 9 (a) “Injection Definition” sets up parcel entrance conditions. 8 pts Injection Points Set 1: Boundary.05 kg/s 1 parcel/point Injection Points Set 1: Line. 8pts Set 1. Wi = –5 m/s mT = 0.02 . 6 pts Injection Points Set 1: Single point Set 2: Line.05 kg/s 2 parcels/point Injection Group 2 Injection Definition Rosin-Ram PDF Vi = 2 m/s mT = 0. 3pts Single Parcel Set 1. All entrance locations defined subsequently are then assigned to one of these groups. User Subroutine — opens a single panel. 6pts Set 2. The concept is illustrated by the example shown in Figure 9-1 below: Droplet Type 1 Momentum ON Heat transfer ON Properties of Heptane Droplet Type 2 Momentum ON Heat transfer OFF Properties of Water Injection Group 1 Injection Definition Constant Diam. “Droplet User Subroutine”.02 kg/s 3 parcels/point Injection Group 3 Injection Definition Normal PDF Wi = 7 m/s mT = 0. 3 pts Set 2: Circle. in terms of either velocity and rotation components or nozzle parameters (b) “Injection Points” defines parcel entrance locations The association between conditions and locations is made by first dividing parcels into injection groups that share the same entrance conditions. 12 pts Set 2. 1pt Injection Point Figure 9-1 Illustration of terminology for explicitly defined parcel injection 3. 12 pts Set 1. that calculates all parcel initial conditions through user coding 9-2 Version 4. choose Post > Get Droplet Data from the main window menu bar to display the Load Droplet Data dialog shown below and perform the same function from there. Alternatively.Chapter 9 LAGRANGIAN MULTI-PHASE FLOW Setting Up Lagrangian Multi-Phase Models Note that the Spray injection and Explicitly defined options are mutually exclusive. Step 5 Check the result of the parcel initialisation process graphically by displaying the parcels in the context of a plot of the domain into which they are launched. i. STAR will take the definitions supplied in subroutine DROICO into account as well as the spray or explicit definitions. as illustrated in Figure 9-2: Figure 9-2 Plot of droplet initial conditions This is done by going to the Post-Processing folder. On the other hand. as explained in the on-line Help text. if you change your mind about which method to use for specifying initial conditions.02 9-3 .e. Thus. panel “Plot Droplets/Particle Tracks” and using the plotting facilities of the “Droplets” tab. User Subroutine may be used in conjunction with either of the above options. pick the other method and overwrite the previous definitions. Version 4. you will need to go back to panel “Droplet Controls”. whose rate of progress through the solution domain can be controlled by the user. Trajectory displays — these show droplet tracks. Alternatively. as shown in Figure 9-3. The circle size and colour can be made to depend on a variety of local droplet properties.02 . Static displays — these show the location of one or more droplets at a given point in time. 9-4 Version 4. The droplets are represented by small circles. they may also be used to show successive positions of a given droplet as it progresses through the solution domain. as illustrated in Figure 9-4. These facilities fall into the following two categories: 1.LAGRANGIAN MULTI-PHASE FLOW Data Post-Processing Chapter 9 Data Post-Processing pro-STAR provides special facilities for visualising the results of a Lagrangian multi-phase flow analysis. either as continuous trajectories or as animated streaks. Figure 9-3 Static display illustration 2. use panel “Plot Droplets/Particle Tracks”.trk) file generated automatically by the STAR-CD solver for Lagrangian flow problems. To do this. the secondary scale will correspond to droplet velocity magnitude. If the droplets are filled with a single arbitrary colour. Step 3 Use the “Droplets” tab controls to choose options appropriate to the plot you want to create.02 9-5 .Chapter 9 LAGRANGIAN MULTI-PHASE FLOW Data Post-Processing Figure 9-4 Trajectory display illustration Static displays Steady-state problems Step 1 Read the required droplet data from the track (. If the plot is a contour plot and the droplet fill colour varies according to a physical property. Step 2 If necessary. Note that a droplet display may be superimposed on a post data plot by choosing Plot > Cell Display > Droplets from the main window menu (or by issuing command CDISPLAY. a secondary scale will be displayed for that droplet property. DROPLET) before the cell plotting operation. The display will then include only locations visited by droplets during this time interval. as represented by the vector colours. and droplet velocity vectors are displayed. Version 4. ON. use command DTIME to specify a time range over which you want droplet track data to be plotted. tab “Droplets”. 5. If the loading choice was Droplet Initial Conditions (see Step 5 on page 9-3) or Current Post Data File (see Step 2 on page 9-8). the following options are available: (a) Cursor Select — click on the desired parcels with the cursor. The set selection facilities available via the D -> or Dp buttons are as follows: 1. 2. the following options are available: (a) Active — select all active parcels (b) Stuck — select all parcels that have stuck to a wall and become immobilised Note that droplet set information is not saved in the restart (. what constitutes a valid option depends on how droplet data were read into pro-STAR: 1. all droplet tracks whose initial positions fall within the current cell set are selected. option Cell Set selects parcels that are contained within the physical space occupied by the current cell set. as described below. In every case. 2. This provides the most extensive range of selection options. Abort the selection by clicking the Abort button. 3. For all loading choices.LAGRANGIAN MULTI-PHASE FLOW Data Post-Processing Chapter 9 Step 4 Select a set of parcels whose progress through the solution domain is to be displayed. If the loading choice was Current Post Data File. 3. 6. splines.02 .mdl) file on completion of the post-processing run Step 5 Display the selected parcels as a series of droplet circles by clicking Droplet Plot in the “Droplets” tab 9-6 Version 4. All — puts all parcels in the set None — clears the current set Invert — selects all unselected parcels and clears the current set New — replaces the current set with a new set of parcels Add — adds new parcels to the current set Unselect — deletes parcels from the current set Subset — selects a smaller group of parcels from those in the current set For the last four items. etc. vertices. sets may be selected by • • • a coloured button marked D -> on the left-hand-side of the main window a similar button labelled Dp in the “Droplets” tab typing command DSET in the I/O window. 4. complete the selection by clicking the Done button on the plot (b) Zone — use the cursor to draw a polygon around the desired parcels. If the choice was Track File (see Step 1 on page 9-5). 7. the target parcels may be assembled by choosing an option from a secondary drop-down list. Thus. Complete the polygon by clicking the last corner with the right mouse button (or click Done outside the display area to let pro-STAR do it for you). The selection procedure is analogous to that described in Chapter 2 of the Meshing User Guide regarding sets of cells. Select the track file and then click Load Data to read in and display all available information in that file. Special data requirements In some situations. choose Lists > Tracks from the main window menu bar to open the Particle/Droplet Track Data dialog. given by command DAGE. Step 6 If detailed numerical information is required on the selected parcels. as shown below: The required information is displayed by clicking the appropriate parcel number (shown in the Track column) with the mouse. The position of a range of parcels at a given point in time. the user may require the following additional information: 1. A parcel’s age is defined as the interval between the time when the first parcel entered the solution domain and the time when the parcel in question hits a wall or exits from the solution domain. The ‘age’ of all currently-loaded parcels.Chapter 9 LAGRANGIAN MULTI-PHASE FLOW Data Post-Processing The locations of the circles represent the points where a parcel intersects cell boundaries as it travels from the beginning to the end of its path through the mesh. The same information (but in a different format) can also be displayed on the I/O window by typing command PTPRINT. as opposed to a specified parcel at a series of time points. Age is calculated from data in the Version 4. Continue by specifying the appropriate parcel set and then use the “Droplets” tab in STAR GUIde to display the required droplet distributions.02 9-7 . Note that the time specified in PTREAD is independent of any time information specified via command DTIME (see Step 2 above) 2. The data needed for such a display may be obtained by interpolation of the available data at the time point in question using command PTREAD. trk) file and may be used as the basis for selecting a parcel set. diameter. using the options provided in panel “Plot Droplets/Particle Tracks” (“Droplets” tab). This file is generated automatically during the Lagrangian multi-phase analysis for both transient and steady-state calculations.LAGRANGIAN MULTI-PHASE FLOW Data Post-Processing Chapter 9 track (. As for particle tracks generated at the post-processing phase. Step 5 Plot droplets by clicking the Droplet Plot button. For example. velocity and other droplet data stored in case. Step 6 Information about a range of parcels at the current time step can also be displayed in the I/O window using command DLIST. as for “Steady-state problems”. These are plotted as continuous trajectories or animated streaks. droplet count and temperature of every second parcel between 1 and 50. the data required for such plots are stored in file case. using STAR GUIde’s “Load Data” panel (“File(s) tab”). Step 2 Open panel “Plot Droplets/Particle Tracks” (“Droplets” tab) and read the contents of the transient file by selecting option Current Post Data File from the pop-up menu at the top.1.trk. mass. This information may be listed in the I/O window using command DLIST.OTHER will list the density. Note that: • • 9-8 It is also possible to print position. pro-STAR will locate the right one automatically. Step 4 Select the desired parcel set using the most appropriate of the methods described under “Steady-state problems”. DLIS. via command DSET. Transient problems Step 1 Decide which time step is to be inspected and then load the corresponding data (from file case.2.trk for each track using command PTPRINT.50. Information on parcel ‘age’ is also obtainable with this command (having first executed command DAGE). The data in this file will be overwritten if the user generates post-processing Version 4. age is defined as the interval between the time when the first parcel entered the solution domain and the current time. If more than one transient file is available. Step 3 Choose appropriate options in the Droplet Plot Options section of the same tab.02 . Trajectory displays Trajectory displays are basically droplet track displays. In transient problems.pstt). engine combustion cases also produce additional output data (. The information in this file may also be displayed in graphical form using the utilities provided in STAR GUIde’s Graphs folder (see panel “External Data”). Average_P Average_T Average_d Meaning Time step number Elapsed time at this time step [s] Crank Angle [degrees] Cylinder absolute average pressure [pa] Cylinder absolute average temperature [K] Cylinder average density [kg/m3] Cylinder_Mass In-cylinder mass [kg] Tot_Inj_Lqui Cur_mas_Fue Evaporated Evaprt_% Leading_par Distance Velocity V_mag Idr Sauter_D AngMom_X AngMom_Y AngMom_Z Mass_Burnt Total injected mass [kg] Total mass of liquid phase [kg] Total evaporated mass [kg] Ratio of total evaporated mass to the total injected mass [%] Unused Unused Unused Unused Unused Sauter mean diameter [m] Fluid angular momentum w. the Z-axis Burnt fuel mass [kg] Version 4. written by STAR if the Lagrangian multi-phase and/or combustion simulations options are in use.t.t. the Y-axis Fluid angular momentum w. the X-axis of the local coordinate system used in the model [kg/m2s] Fluid angular momentum w.r.Chapter 9 LAGRANGIAN MULTI-PHASE FLOW Engine Combustion Data Files particle tracks without first saving the droplet data. The meaning of the quantities appearing in the file is as follows: Name T-Step Time Crank_Ang.02 9-9 .r. Engine Combustion Data Files In addition to the normal results files.r. One such file is produced for every fluid domain in your model and contains both fuel droplet data (represented as globally averaged quantities) and general engine data.t.spd) files. 5.02 . In practice. 4. The dispersed phase should then be introduced and the analysis restarted using the Initial Field Restart option to obtain the desired solution in one iteration only. Complex or unusual physical conditions relating to momentum. i [kg] Note that. Similarly. heat and mass transfer between droplets and the continuous phase can be accommodated by supplying user subroutines DROMOM. a converged solution without the dispersed phase should be calculated. volume of a typical droplet times the number of droplets in the parcel) should not exceed 40% of this cell volume.LAGRANGIAN MULTI-PHASE FLOW Useful Points Chapter 9 %Evap_Burnt Burnt fuel as a percentage of fuel evaporated Heat_Release_R Heat release rate [J/s] ate Scalar Mass of scalar no.e. In transient analyses involving droplets that move faster than their surrounding fluid. 2. heat and mass transfer behaviour of droplets at wall boundaries can be specified by supplying the required relationship via subroutine DROWBC. complete solution. the computer time required may again be reduced by obtaining the solution in two stages. It is recommended that the total droplet volume (i. 3. The above treatment is strictly valid only for droplets whose physical dimensions are appreciably smaller than those of a typical mesh cell through which they travel. it may be beneficial to start the analysis by obtaining a solution that does not include the dispersed phase. 6. The latter should then be introduced into the calculated flow field and the analysis restarted using the Initial Field Restart option to produce the final. STAR-CD’s default treatment for heat transfer coefficients can be combined with user-calculated mass transfer coefficients and vice-versa. First. however. “Load step definition”) should be based on the droplet rather than the fluid velocity. respectively. Useful Points 1. DRHEAT and DRMAST that describe each transfer process. the user will most probably want to use the same calculation procedure for both of them. special conditions relating to the momentum. In steady-state models using the uncoupled approach. the Courant number used for estimating a reasonable time step size (see Chapter 5. If a convergent solution cannot be easily obtained in steady-state models using the coupled approach. depending on the model. 9-10 Version 4. some of the above data may have no meaning. If so. valid only for Eulerian multi-phase flows.Chapter 10 EULERIAN MULTI-PHASE FLOW Introduction Chapter 10 EULERIAN MULTI-PHASE FLOW The theory behind problems of this kind is given in the Methodology volume. Step 2 Set up the mesh and define the boundary region locations as usual. This chapter contains an outline of the process to be followed when setting up an Eulerian multi-phase analysis. pro-STAR checks if another multi-phase simulation option (Lagrangian. Chapter 13. 2. 4. only part of the full STAR-CD boundary type set is available for this kind of analysis. Note that: Version 4. Your problem should not contain more that one boundary of this type. as listed above. “Phase-Escape (Degassing) Boundaries” in this volume).02 10-1 • . ‘Degassing’. within the Thermophysical Models and Properties folder. 5. containing details of the user input required. Inlet Outlet Pressure Wall Non-porous baffle Cyclic Symmetry Degassing Attachment Monitoring • • Note that: The above list contains an additional boundary type. 10. Introduction Setting up multi-phase models Step 1 Switch on the Eulerian multi-phase simulation facility using the “Select Analysis Features” panel in STAR GUIde: Select Eulerian Multi-Phase from the Multi-Phase Treatment menu Click Apply. 8. Free Surface. Cavitation) is already on. • An additional sub-folder called Eulerian Multi-Phase now appears in the NavCenter tree. At present. 9.references to appropriate parts of the on-line Help system. Also included are cross. 6. Step 3 Open the Thermophysical Models and Properties folder and use each of its sub-folders to provide relevant information about your problem. 7. 3. • Only the currently available boundary types. The permissible options are: 1. it issues a warning message and turns it off. This permits dispersed phase mass to escape into the media surrounding the solution domain (see also Chapter 4. can be set up via the “Create Boundaries” panel. 1 is treated as the continuous and no. the “Select Analysis Features” panel does not allow this option. (h) “Buoyancy” — if buoyancy effects are important. The information is supplied in two separate panels: (a) “Drag Forces” — define a model for calculating drag forces directly or via the drag coefficient (b) “Other Forces” — define models for calculating other interphase forces (e. virtual mass and/or lift force) • If heat transfer is present in the analysis. Use the Liquids and Gases panels to specify physical properties and special flow conditions in your model. use the “Interphase Heat Transfer” panel to specify the method of calculating the Nusselt number (and hence the heat transfer coefficient). (c) Chemical reactions of any kind. specify a datum location and reference density.02 10-2 . (b) Where appropriate. specify a method for calculating the turbulence characteristics of both phases and also the turbulence-induced drag (e) “Thermal Models” — if heat transfer is present in the analysis. (d) Liquid films of any kind. (c) “Molecular Properties” — compared to single-phase problems. Of these. no. Therefore. • The current version does not support the following features: (a) Multi-component mixture problems requiring the presence of additional scalar variables in either phase. data are entered per phase. (b) Porous media flow. including coal combustion and the STAR/KINetics package.EULERIAN MULTI-PHASE FLOW Setting up multi-phase models Chapter 10 • • Thermal/solar radiation is not supported in this version of the code. Step 4 In the Eulerian Multi-Phase folder: • Open the Interphase Momentum Transfer sub-folder to specify appropriate models and related parameters for this part of the analysis. The specification process and permissible options are common to both phases. STAR GUIde does not display the Additional Scalars sub-folder.g. 2 as the dispersed phase. Note that: (a) Only a single domain (or material) is allowed at present. The values specified apply to both phases. Again. Therefore. turn on the temperature solver for each phase as required (f) “Initialisation” — specify initial conditions for each phase (g) “Monitoring and Reference Data” — supply a reference pressure and temperature and the cell location corresponding to the reference pressure. therefore the Porosity sub-folder is not displayed. the “Select Analysis Features” panel does not permit the above options to be turned on. so the Material # slider in each panel remains set to 1. (d) “Turbulence Models” — if turbulent flow conditions prevail. only a restricted range of options is available for evaluating physical properties. with the number of phases currently restricted to two. Version 4. Again. these values apply to both phases. especially in parts of the mesh where the volume fraction is close to 1 or 0. Note that the choice of which variables to monitor is phase-dependent. • If you are running a transient problem. Likewise. separate boundary conditions are needed for each phase. The permissible range of boundary types is shown in Step 2. phase-specific data may be plotted in a graph. turbulence or enthalpy equations of either phase. When pro-STAR’s boundary display facilities are used to check the various boundary region definitions (see Chapter 4. A phase slider in the “Data tab” of panel “Load Data” enables you to select the precise data required. “Boundary Visualisation”). Double precision cases have been more extensively tested • • • Step 9 Post-processing the analysis results follows the same rules as single-phase problems. Step 6 Specify boundary conditions using the “Define Boundary Regions” panel. pressure. The choice depends on whether you wish to monitor values at a boundary region or within a cell set. use the “Source Terms” panel in folder Sources to specify mass sources or additional source terms for the momentum. use the “Transient tab” in the “Analysis Output” panel to select which variables you wish to store in the transient post data file (. Step 8 Run STAR in double precision mode. At present. The types of graph available are described in topics “Residual / Monitored History Data”. all particles are assumed to be of equal size. as a function of iteration or time step. open the “Primary Variables” panel and make any necessary adjustments to the current settings • If you wish to monitor the value of any flow variable(s). At present. There are two reasons for this: • Solving the volume fraction equation in this manner gives rise to a smaller truncation error. Step 5 If required by problem conditions.ccm file per phase. Note that the choice of such variables is phase-dependent.02 . multi-phase sources may only be specified via user subroutines. select Output Controls > Monitor Engineering Behavior and then open panel “Monitor Boundary Behaviour” and/or panel “Monitor Cell Behaviour”. 10-3 • Version 4.pstt). Note that: • Analysis data are stored in the . wall/baffle and cyclic regions. This is sometimes essential for convergence of the solution. Step 7 In the Analysis Controls folder: Select Solution Controls > Equation Behavior. inlet phase velocities will be displayed according to the setting of the Phase # slider in panel “Define Boundary Regions”. Note that for inlet.Chapter 10 EULERIAN MULTI-PHASE FLOW Setting up multi-phase models Specify the size of the particles making up the dispersed phase using the “Particle Size” panel. EULERIAN MULTI-PHASE FLOW Setting up multi-phase models Chapter 10 “Engineering Data” and “Analysis History Data”. 2. a maximum residual error tolerance of 1.02 . The momentum under-relaxation factors should be the same for both continuous and dispersed phases. Useful points on Eulerian multi-phase flow 1.3 on momentum for both phases and 0. To ensure satisfactory convergence for steady and pseudo-transient cases. The pressure under-relaxation factor should also be equal to the volume fraction factor. 10-4 Version 4.1 on pressure and volume fraction.0 × 10-6 is recommended. Suggested values for these parameters are 0. which contains details of the user input required. Free-surface flows have to be computed in a time-marching manner. pro-STAR will automatically define such a scalar (if it has not been defined already) on pressing the Apply button in the Select Analysis Features folder. An additional folder called Free Surface will now appear in the NavCenter tree. In the latter case. • Note that: 1. Certain combinations of the free surface model with other STAR-CD features Version 4. as described in Step 7 below. The boundary types currently supported in free-surface problems are: • • • • • • • • • Inlet Outlet Slip and no-slip impermeable walls Symmetry planes Static and piezometric pressure (with both environmental and mean options deactivated) Baffles Cyclic boundaries (except for partial cyclics in which the mass flow rate is specified) Attachment boundaries Monitoring boundaries Step 2: Activate the free surface model Turn on the free-surface option using the “Select Analysis Features” panel of the STAR GUIde system: • • Select On from the Free Surface menu Select option Transient from Time Domain menu. 2. This section contains an outline of the procedure to be followed when setting up free-surface flow problems.Chapter 11 FREE SURFACE AND CAVITATION Free Surface Flows Chapter 11 FREE SURFACE AND CAVITATION The theoretical description of free-surface flow models is given in Chapter 14 of the Methodology volume. A passive scalar named VOF is required for free-surface problems. Free Surface Flows Setting up free surface cases Step 1: Define the mesh and boundary regions Set up an appropriate mesh and define its boundary regions in the usual way.02 11-1 . This scalar stores the volume fraction of the ‘heavy’ fluid in the solution domain (see “Mathematical model” on page 14-2 of the Methodology volume) and requires definition by the user of appropriate boundary conditions. even if the final solution is steady. All standard STAR mesh features are applicable to free-surface flows but this is not also the case for all types of boundary region. Also included are cross-references to appropriate parts of the on-line Help system. one can choose larger time steps or only one iteration per time step to save on computing time. Click Apply. To define their respective material properties. where σ is the surface tension coefficient and R the radius of interface curvature. Note that the HRIC scheme must be selected if you choose to include surface tension in your model. Step 5: Define thermophysical models In the Thermophysical Models and Properties folder: 1. Surface Tension — determines whether the surface tension effect across the heavy-light fluid interface is to be included in the calculations. The default value for this factor is appropriate for most situations. which stands for ‘High-Resolution Interface Capturing’. Step 4: Define material properties The fluid medium in a free-surface problem is defined as a single fluid material possessing two components: a ‘heavy’ and a ‘light’ one. open the “Controls” panel and specify appropriate settings for the following parameters: 1. (b) The Upwind scheme will not provide a sharp interface but it may be used on coarse or poor-quality meshes or when a sharp resolution of the interface is not an issue. Such features are: (a) (b) (c) (d) Eulerian and Lagrangian multi-phase flow Reacting flow Radiative heat transfer Aeroacoustic analysis pro-STAR will issue a warning message if an attempt is made to switch on any of the above features and the free surface model will then be switched off.FREE SURFACE AND CAVITATION Free Surface Flows Chapter 11 are not currently supported. The latter is proportional to σ/R. For each of the heavy and light components. the blending factor should be reduced. There is also a blending factor associated with the scheme. fill in the relevant property values or select materials from pro-STAR’s built-in property database and then click Apply. where the mesh is fine enough to resolve the interface curvature on a scale that results in an appreciable pressure difference. As suggested by the name. The effect is excluded by default as it plays an important role only in small-scale problems. this scheme should be employed if a sharp interface between the heavy and light fluids is to be resolved. go to the Free Surface folder and open the “Molecular Properties” panel.02 . Differencing Scheme — this defines the differencing scheme to be used for the solution of the VOF transport equation: (a) The default scheme is HRIC. 2. If your application involves solid-fluid heat transfer: 11-2 Version 4. Step 3: Define model control parameters In the Free Surface folder. higher values provide a sharper interface but there is a danger of interface alignment with grid lines under unfavourable flow direction. In such a case. Please note that the following are not supported in free-surface cases: i) Stagnation Enthalpy option in the Conservation menu ii) Chemico-Thermal option in the Enthalpy menu (c) Initialise the flow field and turbulence quantities in the “Initialisation” panel. The overall flow conditions should be specified by entering the Liquid and Gases sub-folder. an active scalar named CAV also needs to be defined (b) Apart from CAV. Note that: (a) When the Cavitation option is turned On (see “Cavitating Flows” on page 11-5).Chapter 11 FREE SURFACE AND CAVITATION Free Surface Flows (a) Open the “Thermal Options” panel and then select Heat Transfer On in the Solid-Fluid Heat Transfer section (b) Click Apply (c) As a result of the above.02 11-3 . or select the Laminar flow option if applicable. open the “Gravity” panel and define the gravitational acceleration and its direction with respect to the coordinate system of the solution domain. to choose the Datum Location at a cell that is likely to be always occupied by the ‘light’ fluid. More than one solid domains may be defined in such models. if possible. as well as the reference pressure and temperature. If gravitational effects are important in your application. (e) Use the “Buoyancy” panel to specify whether buoyancy effects are to be included in the calculation. This is designed to supply relevant information for the following aspects of the model: (a) Open the “Turbulence Models” panel and choose an appropriate turbulence model for your case. In the Show Options section. Define ‘active’ and ‘passive’ scalars in the Additional Scalars sub-folder. A passive scalar named VOF should already be defined at this stage. open the “Thermal Models” panel and select the Temperature Calculation On option. 3. choose the enthalpy formulation and transport equation to be solved for it. a sub-folder called Solids will appear in the STAR GUIde tree. 4. Note that radiative heat transfer is not currently supported in free-surface problems. no other active scalar can be defined for free-surface problems (c) You may define as many ‘passive’ scalars as are necessary for your model (d) The diffusion term in the transport equation for all scalars defined in a free-surface model will be switched off Version 4. Only the Constant and User options are supported for free-surface cases. It is advisable to use a Datum Density value corresponding to the ‘light’ fluid density and. (b) If thermal effects are important. Select the On button if this effect is important. (d) Use the “Monitoring and Reference Data” panel to specify the locations of the monitoring and reference cells. 2. Use this sub-folder to define solid material properties. Step 7: Define analysis control parameters Go to the Analysis Controls folder: 1. or assignment according to cell type is applied. In most cases. This is applicable to both cavitating and free-surface flows. (c) Select option Euler Implicit from the Temporal Discretisation menu. click CTAB on the main pro-STAR window to open the Cell Table Editor and use it to set the Initial Free Surface Material switch to Light (for those cell types initially occupied by the ‘light’ fluid) or to Heavy (for cell types initially occupied by the ‘heavy’ fluid). 6. Make any necessary adjustments to the current or default settings in the Equation Status. one can limit the number of outer iterations per time step (see topic “Transient problems” in the STAR GUIde on-line Help) to 1. turbulence.FREE SURFACE AND CAVITATION Free Surface Flows Chapter 11 5. Note that: (a) Only the SIMPLE algorithm is applicable to free-surface problems (b) Both CG and AMG solvers are applicable and the desired one may be selected from the Solver Type menu. Select the Solution Controls sub-folder and then open the “Solution Method” panel to set/adjust the solution algorithm parameters. make sure that both the Envir Press (environmental pressure) and Mean (pressure profile mean value) options are set to Off. (d) If a steady-state solution is expected. For free-surface problems involving porous media. This is the only option supported for this type of problem. either Constant values. Use the Sources sub-folder to define external source terms for momentum. Note that: (a) User Coding is the only supported option in this case (b) The VOF transport equation does not accept additional source terms Step 6: Define boundary conditions Go to the Define Boundary Conditions folder • • Open the “Define Boundary Regions” panel and specify appropriate boundary conditions in the usual manner Open the “Scalar Boundaries” panel and specify boundary conditions for the VOF scalar Valid boundary types for free-surface problems are listed under Step 1. enthalpy and scalars. 2. If a pressure boundary condition is specified. initialize the distribution of the VOF scalar by opening the “Initialisation” panel and choosing one of the available options. Solver Parameters and Differencing Schemes 11-4 Version 4.02 . use the Porosity sub-folder to define properties for the porous materials in the normal way. Select the Equation Behavior sub-folder and then open the “Primary Variables” panel. 7. In the Additional Scalars sub-folder. but one needs to be certain that a steady-state solution can be reached. AMG is recommended since it usually leads to shorter computing times. in which case a pseudo-transient marching towards the steady state is obtained. In the latter case. User coding. (b) Ignore the section concerning the differencing scheme because the latter has already been set in the free-surface “Controls” panel. Fill in appropriate values for simulation time and time step size in the relevant boxes. 3. if you wish. (c) Select an appropriate differencing schemes and other control parameters for all scalars other than VOF. This section contains an outline of the procedure to be followed when setting up cavitating flow problems. Step 8: Define the time step size and run duration There are two ways to define the time step size and the run time length: 1. The Analysis Output sub-folder enables you to specify the frequency of saving solution results in the . Setting up cavitation cases Step 1: Define the mesh and boundary regions Set up an appropriate mesh and define its boundary regions in the usual way. All standard STAR mesh features are applicable to cavitation but this is not also the Version 4. (d) Click Apply before changing to another scalar or exiting from the panel. 6. Also included are cross-reference to appropriate parts of the on-line Help system.8). 5. which contains details of the user input required. In this panel. Select the Monitor Engineering Behavior sub-folder and. each of which contains the time step size and number of time steps to be used for each load step. 4. This is the recommended way of defining time steps. 2.ccm file. you will need to use the Advanced Transients panel by choosing Modules > Transient from the main pro-STAR window. Please note that you need to go through Step 1 to Step 7 before defining load steps using the Advanced Transients panel. use the “Monitor Cell Behaviour” panel to save selected cell data for subsequent plotting against iteration or time step number. Select the Output Controls sub-folder and use the “Monitor Numeric Behaviour” panel to print additional information such as convergence residuals and conservation checks (optional). you can define load steps. if necessary (the default value is 0.02 11-5 . 7. In the “Additional Scalars” panel: (a) Adjust the under-relaxation factor for the VOF scalar. Cavitating Flows The theoretical description of cavitation models is given in Chapter 14 of the Methodology volume. If your application involves a moving mesh defined by an events file.Chapter 11 FREE SURFACE AND CAVITATION Cavitating Flows tabs. Go to the Analysis Preparation/Running folder and open the “Set Run Time Controls” panel. Use the “Switches and Real Constants” panel in the Other Controls sub-folder to set switches and constants for any ‘non standard’ practices. Please check carefully the meaning of each switch and constant and use it only when absolutely necessary. 02 . In the latter case. Click Apply. 2. in which case you may select both the Free Surface and Cavitation options. This typically occurs in applications requiring resolution of a sharp interface between a cavitating liquid and a gas. Combinations of the cavitation and free surface models are supported. The boundary types currently supported in cavitation problems are: • • • • • • • • Inlet Slip and no-slip impermeable walls Symmetry planes Static and piezometric pressure (with both environmental and mean options deactivated) Baffles Cyclic boundaries (except for partial cyclics in which the mass flow rate is specified) Attachment boundaries Monitoring boundaries Step 2: Activate the cavitation model Turn on the cavitation option using the “Select Analysis Features” panel of the STAR GUIde system: • • Select On from the Cavitation menu Select option Transient from Time Domain menu. If both are selected. as described in Step 7 below. • Please note: 1.FREE SURFACE AND CAVITATION Cavitating Flows Chapter 11 case for all types of boundary region. This scalar stores the volume fraction of vapour generated during the cavitation process (see “Mathematical model” on page 14-6 of the Methodology volume) and requires definition by the user of appropriate physical properties and boundary conditions. 11-6 Version 4. a passive scalar called VOF is defined automatically by pro-STAR (unless this definition already exists in the model). Cavitating flows have to be computed in a time-marching manner. even if the final solution is steady. 3. Certain combinations of the cavitation model with other STAR-CD features are not currently supported. one can choose larger time steps or only one iteration per time step to save on computing time. Such features are: (a) (b) (c) (d) Eulerian and Lagrangian multi-phase flow Reacting flow Radiative heat transfer Aeroacoustic analysis pro-STAR will issue a warning message if an attempt is made to switch on any of the above features and the cavitation model will be switched off. pro-STAR will automatically define such a scalar (if it has not been defined already) on pressing the Apply button in the Select Analysis Features folder. An active scalar named CAV is required for cavitation problems. An additional folder called Cavitation will now appear in the NavCenter tree. the saturation pressure may be either constant or user-defined in subroutine CAVPRO. When the cavitation and free surface options are combined. Step 5: Define thermophysical models In the Thermophysical Models and Properties folder: 1. the other two parameters are constants. as described in the previous section. there is a heavy component. degassing and possibly other treatment) strongly affects the cavitation process. Of these. Use the Heavy Fluid tab to define molecular properties for the cavitating liquid. the best choice is always the one based on your own experience. Vapour molecular properties are defined using the “Molecular Properties (Scalar)” panel. Please note that the number of nuclei per m3 of liquid has a strong influence on the amount of vapour generated and therefore requires your own knowledge as to its likely value. a value in the range 1011 — 1014 was found to be adequate. For large-scale. as discussed in Step 3 of the “Free Surface Flows” section. Two tabs labelled Light Fluid and Heavy Fluid will appear. However.Chapter 11 FREE SURFACE AND CAVITATION Cavitating Flows 4. low-pressure systems such as ship propellers and large pumps. high-pressure systems such as engine injectors. as for any other active scalar. Average Nuclear Radius and Number of Nuclei contained in 1 m3 of liquid. the definition of molecular properties for the heavy and light fluids is identical to that for free surface flows. If your application involves solid-fluid heat transfer: Version 4. of which the Light Fluid one is always inactive. Three parameters are needed for the Rayleigh model: the Saturation Pressure. go to the Cavitation folder and open the “Molecular Properties” panel. for cavitation without a free surface. physical properties for the gas component are defined using the “Molecular Properties” panel in the Free Surface folder. there is a heavy component and a vapour component. for cavitation with a free surface.02 11-7 . • For cases involving cavitation only. Although only limited measurement data are available. Step 3: Define material properties The fluid medium in cavitating flows is defined as a single fluid material consisting of two or three components. The STAR-CD default is currently the Rayleigh model but you may also define your own model by choosing the User option from the Model Selection menu. Thus. a light component and a vapour component. • • Step 4: Define model parameters Go to the Cavitation folder and open the “Cavitation Model” panel. Please note that displayed values for surface tension and contact angle will not be used for cases involving only cavitation. You will also need to define the differencing scheme for the VOF scalar. it is well known that liquid purity (affected by filtering. smaller values in the range 106 — 1010 may be more appropriate. The following recommendations can be used in the absence of more specific information: • • For small-scale. When cavitation is combined with a free surface. open the “Thermal Models” panel and select the Temperature Calculation On option. (d) You may define as many ‘passive’ scalars as are necessary for your 11-8 Version 4. More than one solid domains may be defined in such models. Use this sub-folder to define solid material properties. An active scalar named CAV should already be present at this stage. Only the Constant and User options are supported for cavitation cases. 2. (e) Use the “Buoyancy” panel to specify whether buoyancy effects are to be included in the calculation. This is designed to supply relevant information for the following aspects of the model: (a) Open the “Turbulence Models” panel and choose an appropriate turbulence model for your case. Define ‘active’ and ‘passive’ scalars in the Additional Scalars sub-folder.02 . or select the Laminar flow option if applicable. choose the enthalpy formulation and transport equation to be solved for it. defined automatically by pro-STAR. open the “Gravity” panel and define the gravitational acceleration and its direction with respect to the coordinate system of the solution domain. In the Show Options section. a passive scalar named VOF is also defined automatically by pro-STAR. Select the On button if this effect is important. no other active scalar can be defined in cavitation problems. This tracks the distribution of the ‘heavy’ fluid volume fraction.FREE SURFACE AND CAVITATION Cavitating Flows Chapter 11 (a) Open the “Thermal Options” panel and then select Heat Transfer On in the Solid-Fluid Heat Transfer section (b) Click Apply (c) As a result of the above. 3. Please note that the following are not supported in cavitation cases: i) Stagnation Enthalpy option in the Conservation menu ii) Chemico-Thermal option in the Enthalpy menu (c) Initialise the flow field and turbulence quantities in the “Initialisation” panel. (b) Apart from CAV. Note that radiative heat transfer is not currently supported in cavitation problems. You may therefore need to define alternative properties if your vapour corresponds to a different fluid. (c) The default molecular properties of the CAV scalar are those of water vapour. The overall flow conditions should be specified by entering the Liquid and Gases sub-folder. 4. a sub-folder called Solids will appear in the STAR GUIde tree. as well as the reference pressure and temperature. (b) If thermal effects are important. (d) Use the “Monitoring and Reference Data” panel to specify the locations of the monitoring and reference cells. Note that: (a) If the Free Surface option is turned On as well (see “Free Surface Flows” on page 11-1). If gravitational effects are important in your application. one can limit the number of outer iterations per time step (see topic “Transient problems” in the STAR GUIde on-line Help) to 1. click CTAB on the main pro-STAR window to open the Cell Table Editor and use it to set the Initial Free Surface Material switch to Light (for those cell types initially occupied by the ‘light’ fluid) or to Heavy (for cell types initially occupied by the ‘heavy’ fluid). the latter representing the heavy fluid volume fraction. Select the Solution Controls sub-folder and then open the “Solution Method” panel to set/adjust the solution algorithm parameters. enthalpy and scalars. initialize the distribution of the VOF scalar by opening the “Initialisation” panel and choosing one of the available options. (d) If a steady-state solution is expected. make sure that both the Envir Press (environmental pressure) and Mean (pressure profile mean value) options are set to Off. 7. If a pressure boundary condition is specified. Use the Sources sub-folder to define external source terms for momentum. in which case a pseudo-transient marching Version 4. In the latter case. Step 6: Define boundary conditions Go to the Define Boundary Conditions folder • • Open the “Define Boundary Regions” panel and specify appropriate boundary conditions in the usual manner Open the “Scalar Boundaries” panel and specify boundary conditions for the CAV and (if applicable) VOF scalars. Valid boundary types for cavitation problems are listed under Step 1. either Constant values.Chapter 11 FREE SURFACE AND CAVITATION Cavitating Flows model (e) The diffusion term in the transport equation for all scalars defined in the cavitation model will be switched off 5. Note that: (a) Only the SIMPLE algorithm is applicable to cavitation problems (b) Both CG and AMG solvers are applicable and the desired one may be selected from the Solver Type menu. AMG is recommended as it usually leads to shorter computing times. For cavitation problems involving porous media.02 11-9 . turbulence. use the Porosity sub-folder to define properties for the porous materials in the normal way. Note that: (a) User Coding is the only supported option in this case (b) The VOF transport equation does not accept additional source terms (c) When the default Rayleigh model is used. Step 7: Define analysis control parameters Go to the Analysis Control folder: 1. or assignment according to cell type is applied. In most cases. you cannot define additional source terms for the CAV scalar. select option Euler Implicit from the Temporal Discretisation menu. (c) For transient cases. In the Additional Scalars sub-folder. 6. This is the only option supported for this type of problem. User coding. FREE SURFACE AND CAVITATION Cavitating Flows Chapter 11 towards the steady state is obtained. In the “Additional Scalars” panel. • 11-10 Version 4. select a differencing scheme and under-relaxation parameter for the CAV scalar and for scalars other than VOF (the differencing scheme for the latter is set in the free-surface “Controls” panel. in this panel. 2. Select the Monitor Engineering Behavior sub-folder and. 4. you will need to use the Advanced Transients panel by choosing Modules > Transient from the main pro-STAR window. Fill in appropriate values for simulation time and time step size in the relevant boxes. you may want to adjust its under-relaxation parameter). 6.ccm file. but one needs to be certain that a steady-state solution can be reached. if you wish. Please note that you need to go through Step 1 to Step 7 before defining load steps using the Advanced Transients panel. each of which contains the time step size and number of time steps to be used for each load step. The Analysis Output sub-folder enables you to specify the frequency of saving solution results in the . 5. If your application involves a moving mesh defined by an events file. Please check carefully the meaning of each switch and constant and use it only when absolutely necessary.02 . Select the Output Controls sub-folder and use the “Monitor Numeric Behaviour” panel to print additional information such as convergence residuals and conservation checks (optional). 3. however. Use the “Switches and Real Constants” panel in the Other Controls sub-folder to set switches and constants for any ‘non standard’ practices. 7. This is the recommended way of defining time steps. Step 8: Define the time step size and run duration There are two ways to define the time step size and the run time length: • Go to the Analysis Preparation/Running folder and open the “Set Run Time Controls” panel. This is applicable to both cavitating and free-surface flows. use the “Monitor Cell Behaviour” panel to save selected cell data for subsequent plotting against iteration or time step number. Select the Equation Behavior sub-folder and then open the “Primary Variables” panel. Solver Parameters and Differencing Schemes tabs. Make any necessary adjustments to the current or default settings in the Equation Status. you can define load steps. 02 12-1 . 3. an option is provided to specify whether the direction cosines are based on relative or absolute velocities. Rotating Reference Frames Models for a single rotating reference frame Step 1 Go to the “Select Analysis Features” STAR GUIde panel and select option On from the Rotating Reference Frame Status pop-up menu. The angular velocity can vary with time. The required parameters are angular velocity and a local coordinate system whose Z-axis defines the axis of rotation. see Figure 12-1.Chapter 12 ROTATING AND MOVING MESHES Rotating Reference Frames Chapter 12 ROTATING AND MOVING MESHES The theory behind rotating and moving mesh problems and the manner of implementing it in STAR-CD is given in the Methodology volume. The present chapter contains an outline of the process to be followed when setting up a rotating or moving mesh simulation. “Load-step based solution mode”). or (b) a user-defined table. to model axial inflow. The boundaries of the rotating domain are also assumed to be rotating. including details of the user input required and important points to bear in mind when setting up problems of this kind. This activates an additional folder in the NavCenter tree called Rotating Reference Frames. 2. or (c) by giving it a different value at each load step of a transient run (see Chapter 5. it is necessary to specify an equal and opposite spin velocity in the Omega text box of the Boundary Region dialog for walls (see the STAR GUIde “Wall” Help topic). Chapter 13. with the variation specified in (a) user subroutine UOMEGA. Stagnation quantities are also defined using either relative or Version 4. ω = 200 rpm Figure 12-1 Solid body rotation Useful points on single rotating frame problems 1. Similarly. open the “Rotating Reference Frames” panel and select option Single Frame. When a stagnation boundary condition is used. it is necessary to specify a spin velocity in the dialog for Inlet regions. Step 2 In the above folder. To model stationary walls. This enables you to define spin parameters for the material in your model. ROTATING AND MOVING MESHES Rotating Reference Frames Chapter 12 absolute velocities. 4. When turbulence is specified as an intensity (at inlet or pressure boundaries), the turbulence kinetic energy is computed on the basis of static coordinate frame velocities. For stagnation boundaries, the specified intensity uses the same velocity as the stagnation quantities. 5. Boundary velocities are computed in the local rotating coordinate system. This is important in interpreting the information passed to the user subroutines. 6. When post processing results, you may view velocities in either the relative or the absolute reference frame (see the “Coord System tab”, located in the “Load Data” STAR GUIde panel). Models for multiple rotating reference frames (implicit treatment) Step 1 Go to the “Select Analysis Features” STAR GUIde panel and select option On from the Rotating Reference Frame Status pop-up menu. This activates an additional folder in the NavCenter tree called Rotating Reference Frames. Step 2 • Decide how many reference frames are required to model the problem adequately. For example, the two-dimensional mixer problem shown in Figure 12-2 requires two rotating frames. Generate the mesh. • Baffle r = 15 cm ω = 0 rpm Sub-domain 2 Spin index = 2 r = 10 cm ω = 500 rpm Sub-domain 1 Spin index = 1 r = 5 cm Baffle Figure 12-2 Multiple rotating frame illustration 12-2 Version 4.02 Chapter 12 ROTATING AND MOVING MESHES Rotating Reference Frames Step 3 Display the Cell Table Editor by clicking the CTAB button on the main pro-STAR window. Define cell index numbers to correspond to each of the rotating mesh blocks (sub-domains) (see “The Cell Table” on page 3-1). Assign different spin and colour table indices to each cell type, as shown below, for the two rotating sub-domains of Figure 12-2. Note that the table entries for both sub-domains have the same material property reference number since the sub-domains belong to the same fluid domain. Sub-domain 1 Sub-domain 2 Version 4.02 12-3 ROTATING AND MOVING MESHES Rotating Reference Frames Chapter 12 Step 4 Assign all cells within a sub-domain in turn to each of the cell types created above (see “Cell indexing” on page 3-3). Step 5 In the Rotating Reference Frames folder, open the “Rotating Reference Frames” panel and select option Multiple Frames - Implicit. This enables you to specify spin parameters (angular velocities and axes of rotation) for each of the spin indices already defined. In terms of the example of Figure 12-2, zero rotational speed needs to be assigned explicitly to sub-domain no. 2 since its local coordinate system is used in transforming velocities across the sub-domain interface. Useful points on multiple implicit rotating frame problems 1. When modelling multiple rotating reference frame (m.r.f.) problems, it is advisable to check the results carefully and see if they are reasonable and within the limitations of this approach. If this is not the case, one may need to resort to moving mesh methods, such as those described in the section on “Regular sliding interfaces”. Note, however, that a result obtained via the m.r.f. method can always be used as an initial field for a transient moving mesh simulation. This will reduce the time needed to reach a periodic state solution. 2. It is important to ensure that the interface between the different m.r.f. sub-domains is a smooth surface (i.e. a constant-radius surface). This point needs particular attention in all-tetrahedral mesh cases. 3. An angular velocity can vary with time, with the variation specified in (a) user subroutine UOMEGA, or (b) a user-defined table, or (c) by giving it a different value at each load step of a transient run (see Chapter 5, “Load-step based solution mode”). 4. The boundaries of a rotating domain are also assumed to be rotating. To model stationary walls, it is necessary to specify an equal and opposite spin velocity in the Omega text box of the Boundary Region dialog for walls (see the STAR GUIde “Wall” Help topic). Similarly, to model axial inflow, it is necessary to specify a spin velocity in the dialog for inlets. 5. When a stagnation boundary condition is used, an option is provided to specify whether the direction cosines are based on relative or absolute velocities. Stagnation quantities are also defined using either relative or absolute velocities. 6. When turbulence is specified as an intensity (at inlet or pressure boundaries), the turbulence kinetic energy is computed on the basis of static coordinate frame velocities. For stagnation boundaries, the specified intensity uses the same velocity as the stagnation quantities. 7. In cases where the mesh structure changes across the interface between two sub-domains (for example, between two axial turbomachinery stages, with the blades swept in opposite directions): (a) Build each sub-domain separately with its own ‘best fit’ mesh structure, and cell types with different spin indices 12-4 Version 4.02 Chapter 12 ROTATING AND MOVING MESHES Rotating Reference Frames (b) Create a continuous mesh by coupling together the cells layers on either side of the interface using the Couple tool (Create Couples option; see also Chapter 3, “Couple creation” in the Meshing User Guide). (c) Use the Couple tool’s Couple Transform option to replace the coupled cells with polyhedral cells that have a one-to-one cell face correspondence at the interface. 8. Boundary velocities are computed in the local rotating coordinate system. This is important in interpreting the information passed to the user subroutines. 9. When post processing results, you may view velocities in either the relative or the absolute reference frame (see the “Coord System tab”, located in the “Load Data” STAR GUIde panel). 10. The present version of STAR-CD does not support the use of rothalpy (see “Rothalpy” on page 1-5 of the Methodology volume) in combination with the implicit solution technique. Models for multiple rotating reference frames (explicit treatment) Step 1 Go to the “Select Analysis Features” STAR GUIde panel and select option On from the Rotating Reference Frame Status pop-up menu. This activates an additional folder in the NavCenter tree called Rotating Reference Frames. Step 2 • • Decide how many rotating frames of reference are required to model the problem adequately, and the locations of the interfaces. Generate the mesh. The interface between adjacent rotating mesh blocks is defined by pairs of adjacent (but spatially coincident) boundaries, as shown in Figure 12-3. The coincident boundaries are first defined as independent boundary regions using separate sets of vertices and then coupled together as described in Step 7 below. Note that the interface must be either a plane perpendicular to the axis of rotation or a conical section, i.e. a surface generated by rotating a straight line around that axis. Version 4.02 12-5 ROTATING AND MOVING MESHES Rotating Reference Frames Boundary Regions no. 6 no. 5 no. 7 (pressure) (inlet) (pressure) 4 3 2 1 IMAT = 1 cell number ω = 100 rpm 36 35 34 33 40 39 38 37 IMAT = 2 boundary number ω = 500 rpm 64 63 62 61 Chapter 12 circumferential direction no. 8 (inlet) 68 67 66 65 IMAT = 3 ω = 1000 rpm 100 99 98 97 8 12 7 11 6 10 5 9 16 20 15 19 14 18 13 17 (a) 1134 134 135 1034 34 35 1135 33 1035 37 (b) Figure 12-3 Coupled boundary illustration Step 3 Display the Cell Table Editor by clicking CTAB on the main pro-STAR window. Define cell index numbers to correspond to each of the rotating domains (see “The Cell Table” on page 3-1). Assign different material property and colour table indices to each cell type but ignore the spin index. In the above example, cell and material indices 1, 2 and 3 are defined to correspond to each domain. Step 4 Assign all cells within a domain in turn to each of the cell types created above (see “Cell indexing” on page 3-3). Also ensure that separate monitoring cell and reference pressure locations are specified for each domain. Step 5 Go to panel “Create Boundaries” in STAR GUIde, open tab “Regions” and use its facilities to create separate boundary regions at either side of each interface between domains, as shown in Figure 12-3. Step 6 Specify boundary conditions for both sides of an interface using panel “Define Boundary Regions” (only inlet and pressure boundary types are allowed). Example dialog boxes for boundary regions 5 and 6, making up the first interface in the above example, are shown below: 12-6 Version 4.02 Chapter 12 ROTATING AND MOVING MESHES Rotating Reference Frames Step 7 Go back to panel “Create Boundaries” and use tab “Couples” to join the interface Version 4.02 12-7 ROTATING AND MOVING MESHES Rotating Reference Frames Chapter 12 boundaries together. In doing so, you also need to: 1. Specify whether to join individual boundaries from each region on a one-to-one basis, or to couple the two regions to each other as a whole. If the latter is chosen, the value to be imposed on the couple’s pressure boundary is found by an averaging process. For example, the average of the values assigned to boundary region no. 5 in Figure 12-3 is     =  ∑ p i s i ⁄  ∑ s i i = 5  i = 5  8 8 P region 5 (12-1) where p is the pressure and s the area of each boundary face. 2. If necessary, place region couples (as defined above) into separate groups. This enables you to identify boundary faces across which mass must be conserved and is only necessary in problems that have only inlet boundary couples. Such domains are recommended for solving closed loop problems where the flow rate needs to be determined as part of the solution. The groups to balance are specified in the “Rotating Reference Frames” panel (see Step 8 below). Step 8 In the Rotating Reference Frames folder, open the “Rotating Reference Frames” panel and select either option “Multiple Frames - Explicit” or option “Multiple Frames - NR-Explicit”. This enables you to specify: 1. Spin parameters (angular velocities and axes of rotation) for each of the mesh domains already defined. In the above example, domains 1, 2 and 3 have angular velocities of 100, 500 and 1000 r.p.m., respectively. The spin axis is normally common to all domains. 2. Control parameters required by the explicit solution algorithm and, if required, the coupled region groups mentioned in Step 7 above. Useful points on multiple explicit rotating frame problems 1. When modelling multiple rotating reference frame (m.r.f.) problems, it is advisable to check the results carefully and see if they are reasonable and within the limitations of this approach. If this is not the case, one may need to resort to moving mesh methods, such as those described in the section on “Regular sliding interfaces”. Note, however, that a result obtained via the m.r.f. method can always be used as an initial field for a transient moving mesh simulation. This will reduce the time needed to reach a periodic state solution. 2. It is important to ensure that the interface between the different m.r.f. domains is a smooth surface (i.e. a constant-radius surface). This point needs particular attention in all-tetrahedral mesh cases. 3. An angular velocity can vary with time, with the variation specified in (a) user subroutine UOMEGA, or (b) a user-defined table, or (c) by giving it a different value at each load step of a transient run (see 12-8 Version 4.02 Chapter 12 ROTATING AND MOVING MESHES Moving Meshes Chapter 5, “Load-step based solution mode”). 4. The boundaries of a rotating domain are also assumed to be rotating. To model stationary walls, it is necessary to specify an equal and opposite spin velocity in the Omega text box of the Boundary Region dialog for walls (see the STAR GUIde “Wall” Help topic). Similarly, to model axial inflow, it is necessary to specify a spin velocity in the dialog for inlets. 5. When a stagnation boundary condition is used, an option is provided to specify whether the direction cosines are based on relative or absolute velocities. Stagnation quantities are also defined using either relative or absolute velocities. 6. When turbulence is specified as an intensity (at inlet or pressure boundaries), the turbulence kinetic energy is computed on the basis of static coordinate frame velocities. For stagnation boundaries, the specified intensity uses the same velocity as the stagnation quantities. 7. Interfaces between differentially-rotating mesh domains are best placed at positions that do not lie inside recirculating flow fields. 8. Caution should be exercised when using this approach because of the explicit coupling at the special boundaries. The method is most suitable for problems involving strong outflow across the coupled interface. 9. The NR-Explicit option should be chosen over the Explicit option for configurations where the turbomachinery blades are closely packed and/or if a shock wave is expected to hit either of the two coupled boundaries at the interface. 10. Boundary velocities are computed in the local rotating coordinate system. This is important in interpreting the information passed to the user subroutines. 11. When post processing results, you may view velocities in either the relative or the absolute reference frame (see the “Coord System tab”, located in the “Load Data” STAR GUIde panel). Moving Meshes Basic concepts The moving mesh feature is activated by command MVGRID. Changes in mesh geometry can be specified either by pro-STAR commands (i.e. the Change Grid operation in the EVENTS command module), or by user coding included in subroutine NEWXYZ. In this subroutine, the user can vary the geometry of a model by defining vertex coordinates as a function of time. The deformed coordinates are written to the transient post data (.pstt) file and can be loaded and plotted during post-processing. As an alternative, the Change Grid (CG) operation can be used to alter the vertex positions with time. Its distinguishing features are as follows: • The operation is initiated at an ‘event step’ specified by the user and remains active at all subsequent time steps, until the CG operation is explicitly turned off by a termination event, or a new set of CG commands are provided as part of another event step. The main body of the operation consists of a set of pro-STAR commands that 12-9 • Version 4.02 They are of two kinds: (a) Integer parameters in the range 0-999 (b) Real parameters in the range 0-999 Note that pro-STAR restricts the number of active parameters to 99. a special parameter for piston engine problems. User-defined These are specified by the user in subroutine UPARM to provide additional parameters.ROTATING AND MOVING MESHES Moving Meshes Chapter 12 are used while STAR is running (as part of a STAR/pro-STAR interaction process).TRANS followed by either MVGRID. Step 1 Generate the mesh at time t = 0 and issue the following command: TIME. For more detailed information. as follows: • • • Cell removal/addition — (see “Cell-layer Removal/Addition” on page 12-14) Sliding mesh — (see “Sliding Meshes” on page 12-18) Conditional cell attachment and change of fluid type — (see “Cell Attachment and Change of Fluid Type” on page 12-22) (a) (b) (c) (d) (e) (f) (g) Setting up models The main steps for setting up a moving mesh model are outlined below.02 . Program-defined ITER — current time step number TIME — current solution time LSTP — current load step (see Chapter 5. Note that STAR-CD also provides other special operations related to moving meshes. 2.ON or (turn on the moving-grid option. refer to Tutorial 11 in the Tutorials volume. when using subroutine NEWXYZ only) (turn on the transient solution option) 12-10 Version 4. The CG operation uses all the standard pro-STAR facilities and is therefore more flexible and powerful for mesh geometry changes than user coding supplied in subroutine NEWXYZ. calculated on the basis of other parameters supplied by command EVPARM (see “Setting up models” on page 12-15). “Load step definition”) EVEX — last executed event number EVNO — event number to be executed next ETIM — time at which the next event is scheduled YPST — piston position. The parameters used by the CG command set are: 1. • The above commands utilise a set of both program-defined and user-defined parameters that can store anything that is of relevance to the problem description. cgrd mentioned above for the problem shown in Figure 12-4 are as follows: ! Comments like this are allowed by starting the line with “!” VSET.02 Moving mesh illustration 12-11 .ADD.2.VSET. e.ON. EVFILE.EVENT. when using the EVENTS command module) Step 2 (Skip this step only if mesh changes are input through the user subroutine NEWXYZ) Define an event step data file.2.4. in coded form) EVSAVE.1 (save this information as event no.YBOT (clear the vertex set) (add vertices 1 and 2 to the set) (set parameter YBOT equal to the current time) (change the y-coordinates of the vertex set so that they follow the bottom boundary movement) (re-position the mesh vertices between the two boundaries) VFILL.cgrd (get the description of mesh operations from file case.cgrd.Chapter 12 ROTATING AND MOVING MESHES Moving Meshes MVGRID.PROSTAR (turn on the moving-grid option.0 (define an event) EGRID.VRANGE.1.0.TIME VMOD.F.11.1.2.case.NONE VSET.INITIAL.1 *SET.1.evn (initialise the events file) EVSTEP.3.case.YBOT. 1) The contents of file case.1 11 12 9 10 7 8 Y 5 6 3 4 1 m/s X 1 2 Figure 12-4 Version 4.TIME.g.READ. as described in Chapter 2. User-specified offsets can be applied to the actual event time via command EVOFFSET. typically when transferring data from another computer Step 4 Exit from pro-STAR and then run STAR from your session’s X-window.NOSAVE 12-12 Version 4.evn (connect the event file) TRLOAD case.02 . Step 3 • • • If using the method described in Chapter 5. Check the validity of specified events and prepare the events data file for subsequent use via command EVPREP. typically in order to transfer data to another computer read in coded form from a (. define the load step for the transient run. Note that the events data file can be • • written in coded form to a (.evnc) file with command EVWRITE. PROBLEMWRITE. “Running a STAR-CD Analysis”.evnc) file with command EVREAD.pstt (load the transient post data file) STORE ITER 10 (the appropriate events are loaded and executed automatically) GETC ALL (get the cell data) POPT VECT PLTY NORM CSET NEWS FLUID CPLOT QUIT. with command EVDELETE and remaining event steps re-numbered via command EVCOMPRESS. (c) listed on the screen with command EVLIST. Step 6. 2. etc. (b) modified with command EVGET. “Load-step based solution mode”. Command EVUNDELETE restores a previously deleted event step. For example.ROTATING AND MOVING MESHES Moving Meshes Chapter 12 Note that: 1. Step 5 Post-process the data. Save the problem’s data files using commands GEOMWRITE. 10 are: SUBTITLE Results at time step 10 Velocity field EVFI CONN case. or their equivalent GUI operations accessible from the File menu. 3. the commands needed to process time step no. if necessary. An event step can be (a) deleted. 4. Moving grid events normally describe a continuous motion and will therefore remain operational throughout the run. which may be used in an engine model to automatically generate the moving part of the piston mesh.) The message “MESH PREVIEW RUN” should appear both on the screen and in the run-time output (. it is also advisable to give the . cell expansion or contraction).cgrd) command file and the event (. If. vertices. so care must be taken when specifying the post data output frequency. so that all entities are created at the end of the current model and do not compromise earlier events. Flow boundary conditions on boundaries that have moving vertices may result in mass flux into / out of the domain. 7. this can be done via a termination event as follows: EGRID. The only valid option for restart runs is Standard Restart (see the “Analysis (Re)Start” panel in STAR GUIde. an advanced user can readily modify these to suit specific problems. Automatic Event Generation for Moving Piston Problems pro-STAR provides a special command. 10. boundaries. More specifically. 0.run) file when running STAR. 1. a hidden switch has to be set up in pro-STAR as follows: RCONSTANT.NONE 3. Useful points 1. 4. These commands are designed to be used in sequence. MMPISTON. Note that this facility is not available for parallel runs.0 (e.02 12-13 . which is very useful for checking out the mesh set-up. The transient post data (. the moving mesh commands accomplish the following: Starting from a basic mesh.mdl as the current geometry corresponds to the state of the mesh at time step no. Porous media should not be used in areas of the mesh where there is relative internal movement (i.pstt file produced at the end of each stage a unique filename. STAR can be run in ‘mesh preview’ mode only.8) before starting the analysis. caused by the displacements of the boundaries. As the output is standard pro-STAR events and EGRID commands. the grid motion needs to be stopped for whatever reason. events and moving grid commands to completely specify the mesh motion for the STAR solver. You are strongly advised to set the pressure correction under-relaxation factor to a value less than 1. the Change Grid (.evn) file. however.Chapter 12 ROTATING AND MOVING MESHES Moving Meshes Be very careful not to save problem information to file case. This helps to spread the output produced amongst several files and thus ease the data management and manipulation processes.e. 5. 6. If the analysis is split into several stages. To do this. they create the cells. Version 4. (set constant number 4 to 1.pstt) file is usually very large.g. 2. The collapsing cell faces on the outer perimeter of the group form boundaries. Thus. it is also possible to remove part of a layer. 12-14 Version 4. event step and event time) are specified in the EVENTS command module. Cells can be collapsed at the beginning of a given time step or prior to the start of the calculations. within a given tolerance. When cells are restored. A cell layer (or partial layer) has the following properties: • • • • • • • It is defined as a group of cells that is one cell thick in the collapsing direction.e.ROTATING AND MOVING MESHES Cell-layer Removal/Addition Chapter 12 Cell-layer Removal/Addition Basic concepts A cell is removed by collapsing intervening faces between two opposite sides in a given direction. Trimmed (polyhedral) cells can only be collapsed if they have been formed by extruding another cell in the direction of collapse. they reappear next to the neighbours they had at the time of their collapse. those boundaries are also restored.02 . The cells to be removed or added. In the event of cell removal. Note that cell removal or addition changes only the cell connectivity within the mesh. This means that vertices belonging to the removed cells must move with the moving boundary for all subsequent time steps. No more than one layer may be removed at each event step. in which case cells at the edge of the retained section collapse into prisms. If any of their faces were boundaries. entire layers of cells are removed at a given event step. adding a cell layer. but those forming the upper and lower surfaces of the layer may be quadrilateral or triangular. A cell removal or addition event is executed when the current simulation time equals the time specified by the event step. However. This means that layers to be added must have been removed first. Normally. The actual change of mesh geometry has to be specified explicitly through a moving mesh operation of the kind described in “Moving Meshes” on page 12-9. but not both surfaces simultaneously. This is done by moving together the vertices making up the faces. The reverse operation. Either the upper or lower surface of a layer may coincide in whole or part with a boundary. all restrictions on cell removal also apply to cell addition so that: • • • • Only one entire layer (or partial layer) may be restored at each event step. the user has to ensure that: • • The mesh geometry changes in a way that reflects the fact that cells have been removed. The layer must not be composed of tetrahedral cells. is achieved by expanding the removed layer in the direction it was collapsed. Cells remain collapsed until they are restored. The latter case is treated as a special mesh set-up operation and does not affect the solution in any way. Cell layers must be restored in the reverse order in which they were removed. and the time at which to do this (i. The faces which collapse must be quadrilaterals. C2.NEWS.Fluid RP7.TRANS Version 4.1 *SET.Chapter 12 ROTATING AND MOVING MESHES Cell-layer Removal/Addition Setting up models Cell Removal or Addition operations should always be combined with either • • Change Grid operations in the EVENTS command module.CSET *END *LOOP. . The layers to be removed can be given different cell index numbers using command CTABLE. Step 1 Generate the mesh at time t = 0.1 CMOD.CTY.1 *SET.1.3 *DEFINE CTYPE.CTY CSET.3.02 (turn on the transient solution option) 12-15 .1.3 *SET.C1.1 Step 2 Issue the following commands: TIME.6.1.CRANG. The main steps for setting up a model of this kind are outlined below.C2.1.C1. or the user subroutine NEWXYZ. 7 6 5 Cell index 4 Y (2) 3 2 1 X (1) 19 16 13 10 7 4 1 20 17 14 11 8 5 2 21 18 15 Cell number 12 9 6 3 Figure 12-5 Cell layer removal illustration Referring to the example of Figure 12-5 the relevant commands would be: CTAB. cgrd EVSAVE.1 • (get the description of mesh operations from file case. 2 in the local coordinate system) (remove cells with index no.ROTATING AND MOVING MESHES Cell-layer Removal/Addition Chapter 12 MVGRID.ADD.ON. piston rod position COMP 0.TIME.05 EDDIR. e.case.CTYPE.1.2.ADD.CTYPE.TIME.3.015 ↑ ↑ length initial of con. For example EVPARM PISTON 1000.1 EVSAVE.2 EACELL.0.evn (initialise the events data file) • Turn on the Change Grid operation at time t = 0 EVSTEP.LOCAL.1015 ↑ piston location at TDC 12-16 Version 4.DEACTIVATED.3 • Specify cell layer addition.EVENT.1.TIME.08 EDDIR.INITIAL.ALL EVSAVE.1.0.4.6.LOCAL. 1) (list removed cells) • Specify cell layer removal via a cell range EVSTEP. 2 EVSTEP.4.cgrd. ↑ ↑ piston rotating engine speed (rpm) 0.0 EGRID.02 .13 0.PROSTAR (turn on the moving-grid option) Step 3 • Define an event step data file.04 ↑ crank radius 0.2 EDCELL. 1) Specify cell layer removal via the cell type EVSTEP.2 (remove cells in direction no.TIME.1 ECLIST.g.ALL EVSAVE.2 EDCELL. EVFILE. in coded form) (save this information as event no.0.ADD.ACTIVATED.0. The event time can also be specified using global parameters.CRAN.4 (add all cells with index 2) (list added cells) Note that: 1.case.READ.2 ECLIST. assuming the last cell layer removed had index no. if necessary. For example. with command EVDELETE and remaining event steps re-numbered via command EVCOMPRESS. User-specified offsets can be applied to the actual event time via command EVOFFSET. Step 6. or their equivalent GUI operations accessible from the File menu. PROBLEMWRITE. typically when transferring data from another computer Step 5 Exit from pro-STAR and then run STAR from your session’s X-window.Chapter 12 ROTATING AND MOVING MESHES Cell-layer Removal/Addition EVSTEP 1 ↑ event step PCOMP ↑ compression stage 0. 4. An event step can be (a) deleted. Note that the events data file can be • • written in coded form to a (. “Load-step based solution mode”. Check the validity of specified events and prepare the events data file for subsequent use via command EVPREP. Step 4 • • • If using the method described in Chapter 5.02 ↑ piston position 2. Save the problem's data files using commands GEOMWRITE. typically in order to transfer data to another computer read in coded form from a (. etc. as described in Chapter 2. the commands needed to process time step no. “Running a STAR-CD Analysis”.evn (connect the event file) TRLOAD case. (b) modified with command EVGET. Step 6 Post-process the data. 10 are: SUBTITLE Results at time step 10 Velocity field EVFI CONN case.02 12-17 . Command EVUNDELETE restores a previously deleted event step.pstt (load the transient post data file) STORE ITER 10 (the appropriate events are loaded and executed automatically) GETC ALL (get the cell data) Version 4.evnc) file with command EVREAD. (c) listed on the screen with command EVLIST. 3.evnc) file with command EVWRITE. define the load step for the transient run. 7. In such cases the previously removed cell layers can thus be added at positive event times. “Setting Up Chemical Reaction Schemes”. for example. event step and 12-18 Version 4. This enables the interface cells to progressively change their connectivity during the solution. 2. The message “MESH PREVIEW RUN” should appear both on the screen and in the run-time output (. For STAR-HPC runs. 5. 4.e.02 . you need to ensure that the removed cell layers do not collapse towards the inter-processor boundaries.g. 10. You are strongly advised to identify cell layers intended for removal/addition by assigning a unique cell index to each of them.mdl as the current geometry corresponds to the state of the mesh at time step no.run) file when running STAR. You are advised to first run the model in ‘mesh preview’ mode in order to check whether the intended cell removal/addition and mesh movement are carried out correctly. The change of cell connectivity is activated through a ‘cell attachment’ operation. You are strongly advised to set the pressure correction under-relaxation factor to a value less than 1. Sliding Meshes Regular sliding interfaces One way of implementing sliding meshes is the regular sliding interface method. in reciprocating piston engine models where simulation starts with the piston at top dead centre.0 (e. Useful points 1. This is useful. If the simulation includes combustion modelling and the definition of ignition regions (see Chapter 8. This can be done by issuing the following command in pro-STAR: RCONSTANT. (set constant number 4 to 1) 4. 6.NOSAVE Be very careful not to save problem information to file case. respectively) correspond to cells that will never be removed. 3. the removed cell layers and the inter-processor boundaries should always be perpendicular to each other. It is very important to ensure that the locations chosen for reference pressure and field variable monitoring (via commands PRESSURE and MONITOR. 0. Step 5). Cell pairs to be attached and the time of attachment (i. Cell layers can be removed at negative event times. In another words. 1.8) before starting the analysis.ROTATING AND MOVING MESHES Sliding Meshes Chapter 12 POPT VECT PLTY NORM CSET NEWS FLUID CPLOT QUIT. This can be achieved through manual decomposition. make sure that no cells corresponding to these regions have been removed during the time that ignition takes place. ON.2. The main steps for setting up a case are outlined below. two sets of coincident vertices must be defined at that location.0. one for the stationary and one for the moving part of the mesh.Chapter 12 ROTATING AND MOVING MESHES Sliding Meshes event time) are specified by the user in the EVENTS command module. The sliding interface is defined as two coincident boundaries.02 (event step 1 occurs at time t = 0. Step 1 • Generate the mesh at time t = 0.0) (match regions 1 and 2) 12-19 .0 • Issue the following commands: TIME. EVSTEP.PROSTAR (turn on the moving-grid option) Step 2 • Define an event step data file.1. Thus.ATTACH (define boundary region no. The two coincident boundaries have to be defined as different boundary regions and declared as attachment boundaries using the RDEFINE command: RDEF.evn (initialise the events data file) • Perform an initial attachment operation for the relevant boundary pairs (otherwise they will be treated as detached).INITIAL.2 Version 4.0 followed by either EAMATCH.1.case.TRANS (turn on the transient solution option) MVGRID. Setting up models The regular sliding interface method combines both the Cell Attachment and the Change Grid operation in the EVENTS command module.TIME.ATTACH 1.EVENT.1 as an attachment boundary) 0 ↑ alternate wall system (see “Cell Attachment and Change of Fluid Type” on page 12-22 for an explanation of this parameter) 1 ↑ local coordinate system RDEF.1. The cell attachment event is executed when the current simulation time equals the time specified by the event step within a given tolerance. EVFILE. “Load-step based solution mode”.1 (attach boundaries 6 and 2) (EAGENERATE works similarly to CGENERATE.2 EAGENERATE.02 EATTACH.1. or their equivalent GUI operations accessible from the File menu.case. see “Command-driven facilities” on page 2-44 of the Meshing User Guide) (attached boundaries 10 and 1) (save event no.2.1. An event step can be (a) deleted.02 12-20 .1 (get the description of mesh operations from file case. etc.10.READ. if necessary. PROBLEMWRITE.ALL • (attached boundaries 6 and 1) (attach the rest of the boundary pairs) (list out all attached boundary pairs) Turn on the Change Grid operation at time t = 0.1. User-specified offsets can be applied to the actual event time via command EVOFFSET. 4. in coded form) (save this information as event no. with command EVDELETE and the remaining event steps renumbered via command EVCOMPRESS. (c) listed on the screen with command EVLIST.0.TIME.4. 1) • Specify subsequent attachment operations. define the load step for the transient run. e. (b) listed on the screen with command EALIST. The attached boundary set definitions in an event step can be (a) deleted.1.cgrd.6. Command EVUNDELETE restores a previously deleted event step.1 EALIST. (b) modified with command EVGET. EVSTEP. 3. Step 3 • • • If using the method described in Chapter 5.1 RP5. Save the problem’s data files using commands GEOMWRITE. if necessary.ROTATING AND MOVING MESHES Sliding Meshes Chapter 12 or EATTACH. with command EADELETE and remaining definitions re-numbered via command EACOMPRESS. Check the validity of specified events and prepare the events data file for subsequent use via command EVPREP. 2) EATTACH.1 EVSAVE 2 Note that: 1. EGRID.cgrd EVSAVE. 2.6.g. Version 4. evnc) file with command EVWRITE.evnc) file with command EVREAD. Useful points 1. When the model’s mesh is being created. At time t = 0. Step 5 Post-processing the data. cell pairs are detached.mdl as the current geometry corresponds to the state of the mesh at time step no. 10 are: SUBTITLE Results at time step 10 Velocity field EVFI CONN case. which in turn allows larger time steps. They become attached only when an event containing EATTACH or EAMATCH commands is executed. it is very useful to set up a regular boundary numbering scheme at the interface. Step 6. the commands needed to process time step no. or they are deactivated.NOSAVE Be very careful not to save problem information to file case. typically when transferring data from another computer Step 4 Exit from pro-STAR and then run STAR from your session’s X-window.evn (connect the event file) TRLOAD case. 3.02 12-21 . At the initial stages of the analysis. they remain attached until another EATTACH or EDETACH command references them. For example. because this simplifies the specification of cell attachment. If this is the case. where.e. 10.Chapter 12 ROTATING AND MOVING MESHES Sliding Meshes Note that the events data file can be • • written in coded form to a (. “Running a STAR-CD Analysis”. this is equivalent to going from Stage 1 to Stage 4 in a single time step. 2. without shearing). the time step dt should be made equal to dtsl. Once attached in this way. for cylindrical systems dtsl = cell face angle at interface / rotating speed (12-2) Version 4.pstt (load the transient post data file) STORE ITER 10 (the appropriate events are loaded and executed automatically) GETC ALL (get the cell data) POPT VECT PLTY NORM CSET NEWS FLUID CPLOT QUIT. typically in order to transfer data to another computer read in coded form from a (. In terms of Figure 15-1 in Chapter 15 of the Methodology volume. as described in Chapter 2. the solution can be accelerated by using pure sliding only (i. Cell Attachment and Change of Fluid Type Basic concepts Cell attachment permits the following situations to be modelled: 1. for example. For STAR-HPC runs. so care must be taken when defining the output frequency of post-processing data. 8. the flow solution in such a domain can have its own reference pressure and temperature. For example. you need to ensure that the sliding part of the mesh resides completely on one processor. If one cell of an attached pair is deactivated.1. 2. two cell widths) in a single time step. All boundaries belonging to a given region must couple only to boundaries belonging to a (different) unique region. It is advisable to first run the model in ‘mesh preview’ mode in order to check whether the intended cell sliding and mesh movement are carried out correctly. (set constant number 4 to 1. 5. EATTACH commands are allowed only between active cells. If both cells of an attached pair are deactivated simultaneously and then reactivated. The latter enables a fluid domain to become completely cut off from the rest of the flow field. (b) A ‘Change Fluid Type’ operation.) 7. This situation necessitates two kinds of operation: (a) A ‘Cell Attachment/Detachment’ operation. it is also advisable to give the . The message “MESH PREVIEW RUN” should appear both on the screen and in the run-time output (. say on the basis of local flow conditions. the other side reverts to the alternate wall region. to model leaf valves which pop open when the pressure difference across them exceeds a given value. 10. A special type of boundary (‘Attachment’ type) 12-22 Version 4. If the analysis is split into several stages. The complete disconnection of neighbouring cells. one may also slide the mesh by more than one cell width (e. This can be done by issuing the following command in pro-STAR: RCONSTANT. it is illegal for some boundaries from region 1 to couple to boundaries from region 2. 11. The transient post data (.4. In cylindrical systems. 9.pstt) file is usually very large.pstt file produced at the end of each stage a unique filename. while other boundaries from region 1 couple to boundaries from region 3. 4. the time step dt should equal dtsl divided by an integer.run) file when running STAR.ROTATING AND MOVING MESHES Cell Attachment and Change of Fluid Type Chapter 12 In general. Once cut off. This can be used. periodic results are usually reached after about seven revolutions. If accuracy is not at a premium. the EATTACH command must be re-issued. The connection of unconnected neighbouring cells in different fluid domains. This can also be achieved through manual decomposition. 6. This helps to spread the output produced amongst several files and thus ease the data management and manipulation processes.02 .g. This requires a boundary interface to be set up separating the (presently or potentially) different fluid domains. Step 1 • Generate the mesh at time t = 0.4. All conditions defined for a particular event are maintained in the next event unless disabled explicitly. when the designated time for connecting cells is reached. Setting up models The main steps for setting up a cell attachment and change of fluid type case are outlined below.ATTACH 1. 1 as an attachment boundary) 8 ↑ alternate wall or inlet region (could also be of type wall) (boundary region no. The two boundaries must be first specified as different boundary regions and then declared as attachment boundaries (see Figure 12-6) using command RDEFINE: RDEF.ATTACH (define boundary region no. Thus.2.Chapter 12 ROTATING AND MOVING MESHES Cell Attachment and Change of Fluid Type must also be declared at the interface where cell attachment and detachment is to take place.8.8 • Version 4.ATTACH 1. The connection/disconnection event is initiated when the current simulation time equals the time specified by the event step within a given tolerance. it remains attached until it is explicitly detached. the precise connection/disconnection time is determined by the flow solution. STAR performs a cell detachment by connecting the detached cells to an appropriate wall or inlet region.8 RDEF.3.8 RDEF. However. the operation may not necessarily be carried out immediately. Instead. The interface is defined as two coincident boundaries made up of two sets of coincident vertices.1.02 Issue the following commands: 12-23 . Cell attachment/detachment operations are specified in the EVENTS command module. once a boundary pair is attached. The same also applies to the ‘Change Fluid Type’ operation. if they happen to be detached.ATTACH 1.inlet The alternate wall or inlet region is specified in order to enable the code to assign appropriate (wall or inlet) properties to the attachment boundaries. RDEF. 8 is a dummy region) 1 ↑ local coordinate system RDEF. 2. 4.0. 8 numbers 2 1 3 1 4 2 4 3 7 5 8 6 Cell numbers 151.FLUID.1. For the model shown in Figure 12-6: For domain no. 3. 2. 4 Boundary region numbers Y (2) IMAT = 1 Cell numbers IMAT = 1: cells 1-100 IMAT = 2: cells 101-150 IMAT = 3: cells 151-200 X (1) Figure 12-6 Outline of conditional cell attachment operation Step 2 • Assign a material property reference no. 97 1. to each fluid domain using command CTABLE. no. 1) (change the currently active cell type to 1) Version 4. 7.TRANS (turn on the transient solution option) MVGRID.100 CTYPE.CSET For domain no. 152 96.CRAN. Boundary 5. 3.10.02 . 2 (IMAT = 2) CTAB.EVENT. 1 (IMAT = 1) CTAB 1 ↑ cell index FLUID ↑ cell type 3 ↑ colour index 0 ↑ porosity reference number 1 ↑ material property reference number 1 ↑ group number CSET. 6.ON.ROTATING AND MOVING MESHES Cell Attachment and Change of Fluid Type Chapter 12 TIME.2 12-24 (collect together all cells with property ref.NEWS.PROSTAR (turn on the moving-grid option) IMAT = 2 IMAT = 3 1.4.1 CMOD.2. 0 EAMATCH.170 PRES.CRAN.1.10 CMOD. 2 PMAT 2 MONI.NEWS.20.1.3 CSET. 1 and 2: EVSTEP.120 PRES.CSET For domain no.1. no.CSET • (collect together all cells with property ref.151.INITIAL.0E05.20 CMOD.0. 3) Define the monitoring cell and pressure reference for each material type using the MONITOR and PRESSURE commands: For domain no. no. For example.1.5. 2) (collect together all cells with property ref. 1 PMAT 1 MONI.2 (event step no.0E05.3.NEWS.110 STATUS For domain no. 3 PMAT 3 MONI.Chapter 12 ROTATING AND MOVING MESHES Cell Attachment and Change of Fluid Type CSET.10 STATUS For domain no. 1 occurs at time t = 0) (connect regions 1 and 2) 12-25 Version 4. 3 (IMAT = 3) CTAB.case. to connect region nos.200 CTYPE.CRAN.180 STATUS (define the monitoring cell) (define the reference cell and reference pressure) Step 3 • Define an event step data file using the EVFILE command (see Figure 12-6): EVFILE.20 PRES.101.FLUID.150 CTYPE.evn (initialise the event data file) • Perform an initial Attachment and Change Fluid operation for relevant boundary pairs (otherwise they will be treated as detached and the attachment boundary type will become equivalent to a wall).0E05.1.TIME.0.02 . set up a conditional event as follows: EVCND.10) (or EFLUID. if necessary.ADD.3 EAMATCH.ADD.GROUP.20 EVSAVE.2. at time t = 1.1.BRAN. (b) modified with command EVGET. 1 to the ‘detach’ set) (or EDETACH.CRANGE. ECONDITIONAL.2. 1) (enable conditional event no.ROTATING AND MOVING MESHES Cell Attachment and Change of Fluid Type Chapter 12 • Change the fluid material property reference number in region 2 to that in region 1 EFLUID. Step 4 • If it is to be assumed that the valve between boundary regions 3 and 4 opens when the average pressure in region 4 is greater than that in region 3.4 Step 5 • Define all other events required.3 • Enable conditional attachment in an actual event EVSTEP.ENABLE EVSAVE.REGION.ADD.1 (list all cells of type ‘Change Fluid’) (save this information as event no. 3 and 4) (change all cells with cell id.4. if necessary.02 (attach region nos.CTYPE.1.1.ADD.ALL (list all detached boundary pairs) EFLUID. with command EDDELETE and remaining definitions re-numbered via command EDCOMPRESS..ADD.150 (or EFLUID.CTYPE.1.CFLUID.3. issue the following commands: EVSTEP. 1) • If.ADD. with command EVDELETE.101.3.TIME. An event step can be (a) deleted. region no.ADD.TIME.1 (add region no.4 EFLUID. 12-26 Version 4.1.2) EDLIST.ALL EVSAVE. 3) . 2 is to be cut off from the rest of the flow.2 Note that the detached boundary set definitions in an event step can be deleted. EDETACH.2) • List the latest definitions and save the information supplied ECLIST.10 EVSAVE.2. Note that: 1. 20 to fluid no.1.CTYPE. 02 12-27 . 10 are: SUBTITLE Results at time step 10 Velocity field EVFI CONN case. Save the problem’s data files using commands GEOMWRITE. 3. At time t = 0. “Running a STAR-CD Analysis”.Chapter 12 ROTATING AND MOVING MESHES Cell Attachment and Change of Fluid Type (c) listed on the screen with command EVLIST. Check the validity of specified events and prepare the events data file for subsequent use via command EVPREP. Step 8 Post-processing the data. typically when transferring data from another computer Step 7 Exit from pro-STAR and then run STAR from your session’s X-window. or their equivalent GUI operations accessible from the File menu. the commands needed to process time step no. Step 6. Once Version 4.pstt (load the transient post data file) STORE ITER 10 (the appropriate events are loaded and executed automatically) GETC ALL (get the cell data) POPT VECT PLTY NORM CSET NEWS FLUID CPLOT QUIT. etc.evn (connect the event file) TRLOAD case. Useful points 1.evnc) file with command EVWRITE. 10. Step 6 • • • If using the method described in Chapter 5. Note that the events data file can be • • written in coded form to a (. For example. 2. Command EVUNDELETE restores a previously deleted event step. User-specified offsets can be applied to the actual event time via command EVOFFSET.NOSAVE Be very careful not to save problem information to file case. “Load-step based solution mode”. typically in order to transfer data to another computer read in coded form from a (. They become attached only when an event containing EATTACH or EAMATCH commands is executed.evnc) file with command EVREAD. as described in Chapter 2. define the load step for the transient run. PROBLEMWRITE.mdl as the current geometry corresponds to the state of the mesh at time step no. cell pairs are detached. ROTATING AND MOVING MESHES Mesh Region Exclusion Chapter 12 attached in this way. The same facilities can also be used during the actual solution run. When the model’s mesh is being created. e. Testing out parts of events. Note that mesh changes can be classified into • • geometry changes connectivity changes Geometry changes should occur only as a result of the EGRID event. Checking out commands read in by EGRID. Event processing is useful at three different stages of flow modelling and serves the following requirements: 1. must also be noted.g. the mass in the deactivated cells is ‘squeezed out’ into the neighbouring cells. Making corrections as needed and re-executing the events. Note that: • This is possible only if the cells in the group are not connected to any other cells in the model. Only active cells can be excluded. or they are deactivated.g. it is very useful to set up a regular boundary numbering scheme at the interface as this simplifies the specification of cell attachment. more than one adjacent layers may be removed at a time). in combination with mesh changes caused by event execution. the group must first be detached from the rest of the model using a cell detachment event. 2. The mass contained in excluded cells is removed from the solution.and Post-processing Introduction The various mesh motions and connectivity changes caused by the execution of event-type commands can be visualised and verified using special pro-STAR facilities.02 . Working with incomplete events. Thus. There are no other restrictions on the cells that may be excluded (e. by contrast. they remain attached until another EATTACH or EDETACH command references them. as described in the section on “Cell Attachment and Change of Fluid Type”. to see if cells to be attached are adjacent Version 4. Mesh Region Exclusion Basic concepts A group of cells can be excluded from the solution domain by defining an ‘exclude’ event and issuing command EECELL. Moving Mesh Pre. All other events can only cause connectivity changes. These help both in setting up the events (pre-processing) and in examining the results of the analysis (post-processing). • • An important difference with respect to cell deactivation. discussed in the section on “Cell-layer Removal/Addition”. Pre-processing Here the emphasis is on: (a) (b) (c) (d) (e) 12-28 Testing out different event combinations. application of EVLOAD results only in changes to the mesh geometry and not to the mesh connectivity. 3. Cells marked as having changed material type are changed to a different cell type.Chapter 12 ROTATING AND MOVING MESHES Moving Mesh Pre. the ‘original state’. Action commands Commands EVLOAD and EVEXECUTE belong to this category. as defined below. the next EVLOAD command will create fresh ‘original state’ files that correspond to the changes. display them using the correct surface and edge plotting options and create particle tracks. For example. There are two basic components involved in this operation: • Creation of internal tables defining the current status of each cell. Command EVEXECUTE should be used only after a successful EVLOAD operation. Execution of any grid-changing commands read in by EGRID.g. i. EVLOAD is used to ‘load’ all events up to a specified point in time. 2.ACTIVE creates a cell set of the currently active cells. Therefore. are saved. the vertex. These tables can then be used by command CSET via keywords ACTIVE. Thus: • Cells marked as ‘deactivated’ are deleted (equivalent to command CDELETE) and vertex numbers on adjacent cells are changed to reflect their new connectivity. stored in the internal tables mentioned above. These detected errors are highlighted in the plots.RESET restores the model to this original state. Vertices on the common face between two cells marked as ‘attached’ will be merged. Using option OFF with command EVEXECUTE restores the model connectivity to the ‘original state’ defined by EVLOAD.02 12-29 . Post Processing By this stage.e. • Note that.and Post-processing to each other. If the model is changed at this point. use EGRID commands to move the mesh and then EAMATCH to define the attach pairs. DEACTIVE or ATTACHED. e. cell and boundary definitions of the model. the goal here is to generate vertex data for various flow variables (via command CAVERAGE). (f) Using events to generate future events. in general. STAR calls up pro-STAR to alter the grid in some way. This command applies the current status. The internal status tables also retain their Version 4. The first time EVLOAD is called. CSET. The various options of the EVLOAD command deal with different ways of specifying the current time. to the mesh. • • The end result of the above is changes to cell connectivity due to cell removal. Some error checking capabilities are also needed to detect event errors which may have previously gone unnoticed.NEWSET. the mesh geometry applicable to any given point in time is available from the actual solution. Solution run Here. Command EVLOAD. There is also a ‘reset’ option which restores the geometry to the ‘original state’. EVFLAG. Any subsequent plotting is controlled by the PLATTACH options. GRID — processes grid change commands This option is essential if EVLOAD is to be used for changing the mesh geometry when pro-STAR is called by STAR.. The EVLOAD components that can be selectively turned on or off are: 1. COND — executes enabled conditional events 2.. If they do not. attached faces are treated like internal faces and thus are not displayed on any surface plots. 6.. the error is reported and EVLOAD is stopped.GRID (if the GRID flag is not set to OFF.PRE. the error is reported and EVEXECUTE is stopped.. For example. ACTIVE — checks that active cells have non-zero volume.. EVFLAG and EVCHECK modify the behaviour of EVLOAD. This saves CPU time and disk space.OFF operation. This option may be turned off whenever there is no need to backtrack in time. one for pre-processing and the other for post-processing.ROTATING AND MOVING MESHES Moving Mesh Pre. the error is reported and EVLOAD is stopped.. It contains two groups of parameters that can be set independently.. DEACTIVE — checks that deactivated cells have zero volume.TIME. which may be considerable for large models.and Post-processing Chapter 12 original setting.TIME CSET NEWS ACTIVE VSET NEWS SURFACE VSMOOTH . 9. A succeeding EVLOAD command also implicitly performs an EVEXECUTE.. UPARM — calls user subroutine UPARM 3. The option specified with command EVCHECK (PREP or POST) determines which of the two groups is to be set. ATTACH — checks that cell faces to be attached have coincident vertices. Finally. NEWSET — creates a set of cells which fail any tests during EVLOAD. SCDEF — creates scratch files containing the initial mesh state.OFF. the EVLOAD command that follows will cause EGRID commands to be executed repeatedly and ad infinitum) (Note the use of the predefined parameter TIME) EVLOAD. NEWXYZ — calls user subroutine NEWXYZ 5. EVCHECK and PLATTACH belong to this category. for example when EVLOAD is called from STAR. If they do not.UPTO. 8. If they do not. 12-30 Version 4. Note that this particular option only applies to EVEXECUTE. Status setting commands Commands EVFLAG.02 . 4. Command EVFLAG can be used to selectively turn on or off different types of events loaded by EVLOAD. command PLATTACH controls the plotting of attached faces. suppose the following commands are read in by EGRID: . 7. When it is set to ON. • Other properties such as diffusivity and turbulent Schmidt number are stream-dependent and must be set on a stream-wise basis (see Step 3 below) Step 2 Once all scalars are defined.Chapter 13 OTHER PROBLEM TYPES Multi-component Mixing Chapter 13 OTHER PROBLEM TYPES The theory behind flow problems of this kind and the manner of implementing it in STAR-CD is given in the Methodology volume (Chapter 16. subject to the following conditions: Each scalar must be defined only once. By choosing option Select scalar from database (see topic “Fluid Property Database”). Clicking Defaults instructs pro-STAR to fill the remaining boxes with default values (those of air). • • Step 3 Specify the stream-dependent (or material-dependent) scalar properties using the Version 4. pro-STAR then fills in all the required values using data stored in file props. a scalar can be present in some streams but not in others. the change is made permanent by clicking Apply delete an unwanted scalar by clicking Delete Scalar.02 13-1 . The properties of each scalar are specified in the “Molecular Properties (Scalar)” panel. In multi-stream flow problems. “Multi-component Mixing”). in two ways: 1. scroll through them one by one via the Scalar # scroll bar at the bottom of the panel to • • • check all property values in the “Molecular Properties (Scalar)” panel modify a current value by overtyping in the relevant text box. The present chapter contains an outline of the process to be followed when setting up problems involving multiple species and includes cross-references to appropriate parts of the on-line Help system. Multi-component Mixing Setting up multi-component models Step 1 Go to the Thermophysical Models and Properties folder in the STAR-GUIde system and open the “Additional Scalars” sub-folder. By choosing option Define scalar material and then typing in values yourself. molecular viscosity and thermal conductivity. It is important that definition of all material (stream) properties via panel “Molecular Properties” has already been completed before any scalar properties are defined.dbs. The allocation of scalar variables to streams is entirely up to the user. Some scalar physical properties are stream-independent and must be set when the scalar is first defined. The latter contains details of the user input required and important points to bear in mind when setting up problems of this kind. 2. or it can be present in more than one stream. These include molecular weight. specific heat. Set up a scalar variable for each species participating in the fluid mixture. “Load step controls”) and click one of the Scalars Select buttons. Step 8 If a transient analysis is to be performed. Once the settings for all scalars in a given stream are complete. The scalars to be printed or post-processed are selected in the Transient Scalar Selection dialog shown below. Step 6 Specify scalar boundary conditions using the “Scalar Boundaries” panel (Define Boundary Conditions folder). For transient problems defined in terms of load steps. go instead to the Advanced Transients dialog (see Chapter 5. to select which scalars exist in what stream. In multi-stream problems where each stream has a different scalar composition. by clicking the option button corresponding to the desired scalar number. use the “Analysis Output” panel (“Transient tab”) to specify whether cell and/or wall data for selected scalars need to be printed or written to the transient post file. specify the effective mass diffusivity and turbulent Schmidt number for each additional scalar present in your model using the “Additional Scalar Properties” panel (“Porosity” sub-folder). click Apply and then move on to the next stream in your model. this panel enables you. in effect. The button to click depends on whether cell or wall data are needed and whether these are to be printed or written to the transient post file. Step 7 Go to the “Analysis Controls” folder and specify solution control parameters for all currently defined scalars using the “Additional Scalars” panel (Equation Behaviour sub-folder).02 .OTHER PROBLEM TYPES Multi-component Mixing Chapter 13 “Binary Properties” panel. Step 5 If the stream incorporates porous media sub-domains (see Chapter 6 in this volume). Step 4 Specify values for the initial mass fraction of each scalar in each stream using the “Initialisation” panel. Command: 13-2 SCTRANS Version 4. if necessary with a compressible setting. For scalars. “Aeroacoustic Analysis”). For efficient utilisation of computer memory. Also included are cross.3 to 0. 2. pro-STAR allows new scalar species to be added to its built-in property database (see topic “Fluid Property Database” in the on-line Help system). etc. it is possible to read them back into a model by executing an IFILE command (see “File manipulation” on page 17-9). the scalar under-relaxation factors should equal that for the energy equation. 6. For combusting or reacting flows. STAR uses default wall functions for calculating heat and mass transfer at wall boundaries.7. activated via the “Miscellaneous Controls” STAR-GUIde panel. Note that the scalar data are written in the form of appropriate pro-STAR commands (SC. Details of existing scalar definitions can be saved to a file of form case. To do this. A polynomial variation for molecular viscosity and thermal conductivity can be specified in the same way.references to appropriate parts of the on-line Help system.). 4. specify the source strength and distribution using the Scalar tab in the “Source Terms” panel (sub-folder Sources). Aeroacoustic Analysis The theory behind aeroacoustic analysis and the manner of its implementation in STAR-CD is given in the Methodology volume (Chapter 16.02 13-3 . An ideal-gas variation for the density is also recommended. Note that this factor has no effect for scalars calculated by an internal method or by user coding. 5. it is recommended that scalar variable numbers are continuous and start at 1. Thus. Step 9 If the stream incorporates additional sources for any of the scalars. the recommended range is 0. Users can supply alternative expressions for heat and mass transfer coefficients in subroutine MODSWF. it is recommended that the specific heat of both background fluid and active species is defined as a polynomial function of temperature (see reference [1]). SCPROPERTIES. issue command CDSCALAR from pro-STAR’s I/O window. The present section contains an outline of the process to be followed when setting up a problem of this type. this can be done in the “Polynomial Function Definition (Viscosity and Conductivity)” dialog that opens from the “Molecular Properties (Scalar)” panel. 7. SCCONTROL.Chapter 13 OTHER PROBLEM TYPES Aeroacoustic Analysis Note that this process should be repeated for every load step in the transient setup. For thermal problems. containing details of the user input required. For problems involving large changes in temperature. Useful points on multi-component mixing 1. 3.scl for use in other problems. The under-relaxation factors for all scalar transport equations should be set to the same value. Setting up aeroacoustic models Step 1 Switch on the aeroacoustic modelling facility using STAR GUIde’s “Select Version 4. Step 3 Perform the usual model setup in the Thermophysical Models and Properties folder: In particular. making sure that the analysis has converged. Note that STAR-CD returns the logarithmic values of the aeroacoustic sources.OTHER PROBLEM TYPES Aeroacoustic Analysis Chapter 13 Analysis Features” panel: Select On from the Aeroacoustic Analysis menu If a transient analysis mode has already been selected. If you require an initial solution without the overheads of calculating aeroacoustic source terms at the last iteration. Step 5 Use the facilities of the Post-Processing folder to load and display the distribution of the AALS variable. using only cell-based or vertex-based values Useful points on aeroacoustic analyses 1. The aeroacoustic results will be automatically stored in the solution (. You will then need to restart the analysis. By default. The default control parameters required for the numerical solution algorithms are also set and are explained by the on-line Help text. k-ε type turbulence model has been selected in the “Turbulence Models” panel Step 4 Specify initial conditions. simply turn the Aeroacoustic Equation Sources switch Off. you will first need to calculate the antilogarithm of the stored scalar using the facilities of the Post Register Operations dialog (see Chapter 13. 2. turn the switch On and perform one iteration to obtain the aeroacoustic results. Step 2 Open the “Aeroacoustic Analysis” panel. a pop-up panel will appear. If the maximum number of iterations is reached without convergence. warning you that the model must be run in steady-state mode. the Aeroacoustic Equation Sources switch is turned On. and then perform the analysis as usual. Click Yes to confirm your choice and proceed with the analysis. make sure that: A density option appropriate to incompressible flow is selected in the “Molecular Properties” panel • A two-equation. “The OPERATE utility” in the Post-Processing User Guide).02 . Note that an additional folder called Aeroacoustic Analysis will now appear in the NavCenter tree. • • • 13-4 Version 4. Note that the displayed option in the Time Domain menu will automatically change to Steady State.ccm) file as an extra scalar variable called AALS (Aeroacoustic Lilley Source). • Click Apply. enter the required values in the panel and then click Apply. If you wish to make any changes. click Apply. it is important to restart the analysis and run it to convergence. boundary conditions and control parameters and then run STAR as normal. If you want to display the actual values. Film Initialization and Film Boundaries. containing the necessary panels for liquid film analysis. A pop-up panel may appear. Film Physical Models and Properties. formation of liquid films and film interaction with the surrounding fluid and walls. Setting up liquid film models The liquid film model can only be used in transient cases. The basic steps for setting up such a model are as follows: Step 1 Open the “Select Analysis Features” panel in STAR GUIde and turn On the Liquid Films option. Click Apply. Step 2 If necessary. “Liquid Films” of the Methodology volume. The “Film Physical Models and Properties” panel activates the liquid film model for specified film materials and sets up a property table for each of them. Films created for and corresponding to (gaseous) materials in different domains are topologically separate and Version 4. Step 3 The Liquid Films folder will contain a set of four panels called Film Controls. • The “Film Controls” panel sets up the basic film modelling parameters. This option should be selected if either • • droplets are injected into the solution domain and their behaviour needs to be modelled as part of the analysis. Note that: (a) There is a one-to-one correspondence between film materials defined in the “Film Models” tab and fluid domain materials defined in the “Molecular Properties” panel. In such a case. This section contains an outline of the steps to be followed when setting up a liquid film simulation.Chapter 13 OTHER PROBLEM TYPES Liquid Films Liquid Films The theory behind the liquid film model and details of its implementation in STAR-CD is given in Chapter 16. containing panels needed for specifying droplet parameters (see Chapter 9. allow for the presence of droplets in your model by selecting option Lagrangian Multi-Phase from the Multi-Phase Treatment menu and clicking Apply. warning you that the model must be run in transient mode. The Liquid Films folder will appear in the NavCenter tree. and/or droplets are generated by the film itself through a stripping process. Note that film property specifications under the second panel of the above set must be supplied even if there are no films initially present in the problem. The panel also includes a Liquid Film Creation facility that enables you to specify which (wall or baffle) boundary regions cannot support liquid films. “Setting Up Lagrangian Multi-Phase Models” in the CCM User Guide). The Time Domain menu setting will then change to Transient. The Lagrangian Multi-Phase folder will then appear in the NavCenter tree. click Yes to confirm your choice.02 13-5 • . Simulations employing this feature typically involve droplet deposition on wall boundaries. these components are assumed to exchange mass. Assuming that the contour plot mode is already selected. you can use the Evaporates to Scalar entry to specify which liquid film component evaporates to/condenses from which gas component. If the component names match. Each boundary condition is applied to the edges shared by a film and a non-film region. the partial pressure of each component on the gas side of the interface should be calculated using subroutine LQFPRO (see the “Multi Component” on-line Help topic) • The “Film Initialization” specifies film initial conditions for each boundary region that can support films. if no boundary conditions are specified for a given variable. it is recommended that the solver be run in double precision. ii) If the Evaporates to Scalar setting for a liquid film component is NONE. the matched components are assumed to exchange mass. In the latter case. The currently available boundary condition types are Outlet and Inlet. the film thickness on that region is assumed to be zero. Step 5 Analysis results pertaining to films are treated by pro-STAR as wall data.02 . in both the “Post tab” tab and the “Transient tab” tab.OTHER PROBLEM TYPES Liquid Films Chapter 13 their liquid contents do not mix with each other. (b) In the “Film Properties” tab.ccm and . respectively. • Step 4 Specify initial conditions. pro-STAR assigns names such as LFTHK (film thickness) and LFT (film temperature) to film variables.pstt files. • In multi-component liquid film simulations: (a) The specified single value of binary diffusivity is assumed to apply to all components in the film mixture (b) For problems involving evaporation from the film surface. boundary conditions and solution control parameters for the domain material (normally gas) surrounding the film and then run the STAR solver as normal. the following rules are used: i) If a liquid film component and a droplet component evaporate to the same scalar. If no initialization is specified. To determine which droplet component becomes which liquid film component when a droplet hits a wall. Due to internal parameter settings and having to work with possibly very small numbers such as film thickness. then this component name is compared against each droplet component name (for single-component droplets.e. Such data items appear in the scroll lists of panel “Analysis Output”. A complete list can be obtained by issuing the PLIST command from the I/O window. so that you may select what is to be included in the . the droplet name is taken as the component name). the cell value is used as an inlet value (i. a Neumann condition applies). The “Film Boundaries” panel sets up film boundary conditions. a typical pro-STAR macro to plot a scalar film variable is: 13-6 Version 4. Chapter 13 OTHER PROBLEM TYPES Liquid Films trlo. use getb lu.. at a point just before the first droplet tracking stage in a new time step. 2. If active. Via an internal stripping model. currently available as a beta feature (see Chapter 13 of the Supplementary Notes volume). LFV. which has previously been defined in pro-STAR. the following commands may be useful for selecting only liquid film cells on the fluid side of the interface: cset newset fluid cset add atsh cset subs name wall To load film velocity components (LFU. as for normal injected droplets. If droplets are generated solely by the stripping process. Obviously. including initial injection velocity and global position coordinates. store last clrw getb lfthk cset news shell cset subs name wall wplot In conjugate heat transfer cases. LFW) as a vector. Via user subroutine FDBRK. The user code must provide all necessary information regarding the new (stripped) droplets leaving the film. The new (stripped) droplets must have a type associated with them.lw Film stripping This process can be modelled in two ways: 1.02 13-7 . the subroutine will be called at all wall faces containing films. it is still necessary to define droplet properties in advance. Version 4.lv. droplet properties should be consistent with those of the parent film. . The latter are collectively referred to as UFILE routines. 5. 16. 3. 25. via user-supplied FORTRAN subroutines. 7. mass and momentum transfer in two-phase Lagrangian flow Droplet initial conditions and physical properties Droplet behaviour near walls Inter-droplet collision modelling Eulerian multi-phase drag. 9. 17. 12. The full set of currently available user programming inputs comprises: 1. 18. 28. turbulence and heat transfer Chemical reaction rates and chemical species mass fractions Chemical species and thermal NOx sources Parameters for sliding mesh and rotating reference frame problems Moving mesh coordinates Cell layer removal or attachment Initial conditions Formation and behaviour of liquid films on walls and baffles Wall functions for momentum. 30. 24. enthalpy and turbulence sources Solar and gaseous radiation properties Free surface and cavitation models and properties Heat. additional sources of momentum. boundary conditions.Chapter 14 USER PROGRAMMING Introduction Chapter 14 USER PROGRAMMING This chapter describes how the user can modify or supplement some of the standard features and operations of STAR. 4. 31. 8. 11. 29. 6. 23.02 14-1 . 20. 26. such as physical properties. 15. Boundary conditions Density (equation of state) Molecular viscosity (including non-Newtonian flow) Specific heat Temperature to enthalpy conversion and vice versa Thermal conductivity Molecular diffusivity for chemical species Properties of distributed resistance Thermal and mass diffusion within distributed resistance sub-domains Effective viscosity and turbulence length scale Turbulence model parameters (including two-layer models) Turbulence characteristics within distributed resistance sub-domains Local injection or removal of fluid Momentum. 10. 19. 14. etc. 32. 21. heat and mass transfer Time-step size for transient problems Special post-processing Variation of blending factor for higher-order discretisation schemes Introduction Subroutine Usage To use UFILE routines you must execute the following steps: Step 1 Create a subdirectory called ufile under your present working directory as Version 4. 27. energy. 13. 22. 2. If you are doing this from scratch. If you want to inspect the dummy subroutine listing before proceeding further. it must be copied into its own individual file within the ufile directory created earlier. A file of the right name containing the right dummy subroutine will be created automatically. their description and the pro-STAR command that activates them. Selecting any line with the mouse displays the default (dummy) code for that subroutine in the upper part of the box. go to the main pro-STAR window and select Utility > User Subroutines from the menu bar. The relative size of the two sub-windows can be adjusted by dragging the control ‘sash’ (the small square on the right-hand side) up and down.USER PROGRAMMING Subroutine Usage Chapter 14 follows: • • • Choose File > System Command from the menu bar to display the System Command dialog Type ufiles in the command text box Click Apply and then Close Step 2 Select the User option in the appropriate STAR GUIde panel or pro-STAR command. Step 3 Before a user routine can be used. depending on the special feature that needs to be modelled. The lower one lists all subroutine names. This activates the User Subroutines dialog shown below. click Define user coding in your current panel. as discussed in “Description of UFILE Routines” on page 14-5. it is convenient to start by copying a skeleton (dummy) version of the relevant subroutine into ufile. • If you want to do this immediately.02 . • 14-2 Version 4. The dialog box is made up of two sub-windows. f. or an existing subroutine is to be replaced. Note that generating a subroutine file in this way is necessary only if • • • Version 4.f. 2. Automatically — click the Write Auto button. Note that if more selections are made after the above dialog box has been opened. a new file will be created called Usubname.new. it is necessary to update the display of selected routines by clicking the Update List button. This copies all subroutines already selected implicitly via the User option in the various STAR GUIde panels (or via the corresponding pro-STAR commands). Explicitly — click the Write File button. or you are updating user code from an earlier version of STAR-CD. In Unix systems.02 the subroutine is to be set up for the first time.Chapter 14 USER PROGRAMMING Subroutine Usage Command: USUBROUTINE The required subroutine(s) may be copied into the ufile directory in one of the following ways: 1. Such subroutines are also marked in the above list with an asterisk. If a file of the same name already exists in the ufile subdirectory. 14-3 . the subroutine file names are of the form Usubname. This copies the subroutine that is currently on view. while keeping the source coding as brief and simple as possible. Default user routines for all modelling functions listed in the “Introduction” are supplied. boundary. The IMPLICIT typing above can be overruled by an explicit declaration of type.g. so a penalty is paid in terms of execution time when they are active.02 . by implementing suitable checks and by printing appropriate diagnostic messages whenever necessary. Useful points As a general rule. designed to ensure that the routine uses the same precision as STAR itself. C. This is in fact what comdb. the increase in CPU time may be minimised through efficient programming. They are then compiled and linked to the main program modules (see Chapter 17. described in a nomenclature text stored in file nom. 3. e.f within the ufile subdirectory. for example by using pro-STAR’s built-in file editor (see the section on “File manipulation” on page 17-9). while those beginning with I through N are INTEGER variables. This is necessary in order to either • • utilise some or all of the existing example coding (by removing the comment character. the file contains a single line C IMPLICIT DOUBLE PRECISION (A-H. those beginning with the letters A through H and O through Z being REAL variables.inc in the ufile directory. containing sample coding. REAL ITIME makes ITIME real and INTEGER ZVAL will make ZVAL an integer. a variable is given a type based upon its initial letter.O-Z) 14-4 Version 4. or add other coding. You should ensure that results produced by user code are reasonable and physically meaningful. Most routines are called for every cell. or droplet (as appropriate for the routine and model in hand). However. as appropriate.USER PROGRAMMING Subroutine Usage Chapter 14 Step 4 Edit the existing or newly-created subroutine file as required. IVAL and JUNK are integer. user routines should be written with due care. “pro-STAR environment variables”). 2. Note that STAR will issue a warning message if it does not find any of the required subroutines but will carry on with the run all the same. Each routine has appropriate input data. ANGLE and SPEED are real but NUMI. It is also possible to change the scope of the IMPLICIT typing. Older files bearing the same name should either be overwritten or renamed. Once the above process is complete. Thus. According to this. the required user routines are automatically passed on to the STAR-CD system in source form. It should be noted that: 1.inc. This is done by exploiting the IMPLICIT typing construct present in FORTRAN. Step 5 The version of a subroutine that is to be used in the current run should always be located in a file called Usubname.inc does: (a) When STAR is used in single-precision runs. from the beginning of the line). TIME. Each routine includes a file called comdb. Version 4. if applicable. That way the routine will be compiled with the correct precision. including the local coordinate system for the velocity components. or by command RDEFINE. or more generally the “default” value from the pro-STAR panel. the file reads IMPLICIT DOUBLE PRECISION (A-H. v. The latter will be in a rotating frame if this was originally specified. (b) When STAR is used in double-precision runs. the boundaries comprising the region are first defined in the usual way. BCDEFI Specifies distributions for all dependent variables that vary spatially over an inlet boundary. The variables in the argument list are never passed uninitialised: they always have a sensible value. Typical input data for a subroutine includes the following: • • • • • • • • Cell number Global Cartesian or user-defined local coordinates of the cell centroid Cell table numbers as defined in pro-STAR Material numbers Porous media sub-domain numbers Iteration number Time Nodal values of the field variables For more information on input data for the UFILE routines.inc). which is usually the value from the previous iteration/time step. thus preserving the standard implicit typing of real and integer variables. A brief description of each subroutine and how it is activated from pro-STAR is given in the next section. the rotational speed of the coordinate frame and any default boundary values that become input values for the subroutines. The coordinates passed to the subroutine are defined in the local coordinate system of the boundary and u. see the nomenclature file (nom. variables should be named according to the IMPLICT typing shown above.Chapter 14 USER PROGRAMMING Description of UFILE Routines which is just a comment. The transformation to the global Cartesian coordinate system is done by STAR.O-Z) This means that the IMPLICT typing has been overruled to use double-precision real variables. The implication for users is that to make sure a routine works correctly. Description of UFILE Routines Boundary condition subroutines The first ten of the subroutines listed below (all those with names starting with BCD) are activated from the Options menu in the Define Boundary Regions panel. In order to use them. w are the corresponding velocities.02 14-5 . They specify spatial variations of the boundary conditions at various boundary types. turbulence intensity.e. chemical species mass fraction and heat and mass fluxes. Specifies boundary conditions at transient wave transmissive boundaries. in problems where wall functions are used for modelling flow near the wall. It specifies the thermal conductivity within a material in heat transfer problems. Specifies boundary conditions at pressure boundaries. pressure and temperature. 14-6 Version 4. Activated from the Roughness menu in the Define Boundary Regions panel for walls and baffles. length scale. In addition.USER PROGRAMMING Description of UFILE Routines Chapter 14 BCDEFO Can be used to specify variations in flow split or mass outflow at outlet boundaries (e. Specifies boundary conditions at Riemann invariant boundaries. can all be varied over the specified region. e.g.g. The thermal conductivity can vary both spatially and with temperature.02 . velocity components. or by command RDEFINE. STAR will default to the smooth-wall behaviour should you activate this subroutine but provide no code for it. pressure and temperature.g. velocity components. Specifies non-uniform boundary conditions at free-stream transmissive boundaries. pressure and temperature. It specifies a user-supplied wall roughness model. including moving wall velocities in local coordinates and in a rotating reference frame. or by command CONDUCTIVITY. Specifies boundary conditions at non-reflective pressure boundaries Specifies boundary conditions at stagnation boundaries Specifies boundary conditions at non-reflective stagnation boundaries Specifies variations in wall boundary conditions. i. temperature and species mass fractions. pressure. BCDEFP BCDNRP BCDEFS BCDNRS BCDEFW BCDEFF BCDEFT BCDEFR ROUGHW Material property subroutines CONDUC Activated from the Conductivity menu in the Molecular Properties (Liquids and Gases) panel or Material Properties (Solids) panel. e.g. velocity components. wall temperature. in a transient run). e. T ( h . The activation works in an exclusive manner. and (b) the variation of temperature T with enthalpy h and any other scalar variable.g. The activation works in an exclusive manner. T ( h . i.02 14-7 .g. h ( T . it is also necessary to supply the relevant partial derivatives ∂h ⁄ ∂m k . in any way chosen by the user (e.e. it is also necessary to supply the relevant partial derivatives ∂h ⁄ ∂m k . m 2 . … ) . h ( T .e. in any way chosen by the user (e. m 1 . Obviously. m 2 . CONVTE and SPECHT. … ) . The activation works in an exclusive manner. The returned values are valid over a specified temperature range. i. STAR also requires the inverse relationship. CONVTE description above) in favour of a supplied relationship. i. … ) . using an efficient iterative technique. … ) .e.e.e. It is helpful (but not essential) to assist the iteration process by supplying ∂h ⁄ ∂T . i. choosing this option excludes use of subroutines CONVTE. choosing this option excludes use of subroutines CONVET. analytically or by means of a table). m 1 . i. COTEET and SPECHT. h ( T . It supplies two relationships: (a) The variation of enthalpy h with temperature T and any other scalar variable. i. T ( h . m 2 . m 2 . These should be valid over a given temperature range. COTEET and SPECHT. It supplies the variation of enthalpy h with temperature T and any other scalar variable. the two relationships must be consistent. m 2 . m 2 . … ) . Activated from the Specific Heat menu in the Molecular Properties (Liquids and Gases) panel or by command SPECIFICHEAT. If the relationship involves other scalar variables. m 1 .Chapter 14 USER PROGRAMMING Description of UFILE Routines CONVET Activated from the Specific Heat menu in the Molecular Properties (Liquids and Gases) panel or by command SPECIFICHEAT. It supplies the variation of temperature T with enthalpy h and any other scalar variable. CONVTE COTEET Version 4.e. it is necessary to supply values for the partial derivatives ∂T ⁄ ∂h and ∂T ⁄ ∂m k . i.e. m 1 . If enthalpy is dependent on a scalar variable. The COTEET option should be used if the user wants to bypass STAR’s internal calculation procedure for the inverse temperature/enthalpy relationship (see the CONVET. for internal calculation purposes and inverts T automatically. for internal calculation purposes and inverts h automatically using an efficient iterative technique. The range of validity of the relationship should be specified in terms of a corresponding range in the values of T. analytically or by means of a table). m 1 . If additional scalar variables are involved. Activated from the Specific Heat menu in the Molecular Properties (Liquids and Gases) panel or by command SPECIFICHEAT. m 1 . STAR needs the inverse relationship. choosing this option excludes use of subroutines CONVET. … ) . Activated from the Resistance Coefficients menu in the Resistance and Porosity Factor panel or by command POROSITY. the global Cartesian velocity components are supplied to the subroutine. This facility is a useful alternative way of specifying a non-linear variation of porous resistance with velocity. k 3 ) directly instead of via the resistance coefficients α and β. It supplies functions for the calculation of effective thermal conductivity and turbulent Prandtl number within a distributed resistance sub-domain. Activated from the Resistance Coefficients menu in the Resistance and Porosity Factor panel or by command POROSITY. It defines spatially varying coefficients α and β within a distributed resistance sub-domain. Activated from a menu in the Turbulence Properties (Porosity) panel or by command PORTURBULENCE. Activated from a menu in the Thermal Properties (Porosity) panel or by command POREFF. For compressible flow cases where density is a function of pressure. k 2 . It supplies equations of state for density calculations that are not included in the standard options. The user can also specify them in terms of a local coordinate system. For this purpose.USER PROGRAMMING Description of UFILE Routines Chapter 14 DENSIT Activated from the Density menu in the Molecular Properties (Liquids and Gases) panel or by command DENSITY. It defines the resistance components ( k 1 . the routine must also specify the partial derivative ∂ρ ⁄ ∂ p and return it in parameter DENDP. Activated from a menu in the Additional Scalar Properties (Porosity) panel or by command SCPOROUS.02 . Activated from the Material Mass Diffusivity menu in the Binary Properties (Additional Scalars) panel or by command DIFFUSIVITY. It supplies the molecular diffusivity of the background material in multi-component mixing problems. It supplies functions for the calculation of effective mass diffusivity and turbulent Schmidt number within a distributed resistance sub-domain. DIFFUS PORCON PORDIF PORKEP POROS1 POROS2 14-8 Version 4. It specifies non-uniform distributions of turbulence intensity and dissipation length scale within a distributed resistance sub-domain. The activation works in an exclusive manner. The subroutine supplies the spatial variation of dissipation length scale (l) required by the k-l model. at constant pressure. “Subroutine THDIFF Set-up” in the Supplementary Notes volume) This subroutine is activated from the Molecular Viscosity menu in the Molecular Properties (Liquids and Gases) panel or by command LVISCOSITY. VISMOL Turbulence modelling subroutines LSCALE Activated automatically when the k-l model is selected via menu option k-l in panel Turbulence Models (Turbulence tab).e. It is particularly useful in modelling combusting or reacting flows exhibiting substantial variation in the value of this property. but its principal use is for supplying functions that describe non-Newtonian viscous behaviour. i. It defines the user’s own formulation of turbulent behaviour in problems using a two-layer model. The subroutine specifies the turbulent viscosity distribution for a turbulent flow calculation. Activated from the Two-Layer Model menu in the Turbulence Models panel (Near-Wall Treatment tab) or by command TLMODEL. This subroutine is activated from panel Turbulence Models (Turbulence tab) or by command TURBULENCE. It can specify an arbitrary distribution of molecular viscosity. or by command SPECIFICHEAT. STAR calculates the temperature T from the iterative expression T (n) h = --------------------(n – 1) (cp) (14-1) where n is the iteration number and c p is the mean specific heat.Chapter 14 USER PROGRAMMING Description of UFILE Routines SPECHT Activated from the Specific Heat menu in the Molecular Properties (Liquids and Gases) panel or Material Properties (Solids) panel. choosing this facility excludes use of subroutines CONVTE.02 14-9 . TWLUSR VISTUR Version 4. The subroutine supplies the variation of fluid or solid mean specific heat with temperature and other quantities. CONVET and COTEET. THDIFF Specifies a user-supplied method of calculating the thermal diffusion coefficient for chemical species scalars (see Chapter 5. It can also be activated by command TURBULENCE. It allows the user to redefine the source term components for the k and ε equations. to account for special effects due to streamline curvature. etc. e. Activated from the Define Source menu in the Source Terms panel (Momentum tab) or by command RSOURCE. effectively replaces the built-in source terms. Thus the user. It specifies additional enthalpy sources or sinks due. Alternatively. ZP or the cell table number ICTID. use command RSOURCE. chemical or nuclear reaction and thermal radiation. This is not required when fluid is removed. the properties of the injected fluid.USER PROGRAMMING Description of UFILE Routines Chapter 14 Source subroutines FLUINJ Activated from the Define Source menu in the Source Terms panel (Mass tab). turbulence parameters. i. global Cartesian coordinates XP. etc. The subroutine initiates fluid injection or removal at specified cells and at a prescribed rate (in units of kg/s/m3). It can also fix the temperature value within a cell by making S1P=GREAT* T fix and S2P=GREAT. SORENT SORKEP SORMOM 14-10 Version 4. magnetic fields.02 . for example. The source terms must be specified per unit volume and linearised as S1P-S2P* φ P . where φ P is the value of the velocity component in question at node P (see the Methodology volume for details). Note that the quantities S1P and S2P in the example code are the ‘standard’ source and sink terms given in the Methodology volume. The cells in which to insert these sources can be selected by their indices IP.e. In the case of injection. The two components S1P and S2P must be separately specified for the U. Activated from the Define Source menu in the Source Terms panel (Turbulence tab) or by command RSOURCE. The subroutine can also be used to fix the value of k. to electric or magnetic fields. Activated from the Define Source menu in the Source Terms panel (Enthalpy tab) or by command RSOURCE. in modifying or supplementing the standard expressions. V and W momentum equations. It enables the modelling of additional momentum source terms. for example due to magnetic or electric fields. YP. temperature. must also be prescribed. where T fix is the desired fixed temperature value and GREAT is a large number used internally by pro-STAR.g. velocity components. It specifies the number of bubble nuclei per cubic metre and a functional relationship between equilibrium radius and cell pressure. Alternatively. In transient problems. It is activated from the Parameters for BTF Model menu in panel Cavitation Model or by command CAVNUCLEI. use command RADPROPERTIES. it enables specification of solar angle and intensity at every time step of the analysis. for example.Chapter 14 USER PROGRAMMING Description of UFILE Routines SORSCA Specifies additional source terms for the scalar variable equations and is activated from one of the following locations: (a) The Define Source menu in the Source Terms panel (Scalar tab) or by command SCSOURCE. It specifies non-uniform distributions of absorptivity and scattering coefficients within the medium filling the space between radiating boundaries. In this case the source terms are used to specify a special cavitation model. Radiation modelling subroutines RADPRO Activated from the Radiative Properties menu in panel Thermal Models (Liquids and Gases) when radiation with participating media is turned on. RADWAL USOLAR Free surface / cavitation subroutines CAVNUC This subroutine is required only in cavitation problems using the bubble two-phase model. in the same manner as that described above for enthalpy. the chemical kinetics and rate expressions of a combustion process. (b) The Model Selection menu in panel Cavitation Model or by command CAVITATION. The source terms might consist of.02 14-11 . Specifies a user-supplied method of calculating radiative properties for solid walls (see Chapter 6. May also be activated from the Radiative Properties (Solids) panel if solid-fluid heat transfer is turned on. “Surface Properties” in the Supplementary Notes volume) Activated from the Define Parameters menu in the Thermal Options panel (Solar Radiation section) or by command SOLAR. The mass fraction value at selected cells can also be fixed via the source terms. Version 4. USER PROGRAMMING Description of UFILE Routines Chapter 14 CAVPRO This subroutine is needed in cavitation or free surface problems requiring variable properties. (b) The Saturation Property Variation menu in panel Mass Transfer (Free Surface folder) or by command VAPORIZATION. It supplies information about average droplet properties calculated while tracking a droplet parcel through the solution domain. Alternatively. Alternatively. COMDEN Calculates species density and its derivative with respect to pressure and temperature for compressible free-surface flows (see Chapter 1 of the Supplementary Notes volume) Activated from the Vaporization Rate menu in the Mass Transfer panel (Free Surface folder). Activated from the Droplet Averaging menu in the Droplet Controls panel or by command DRAVERAGE. It then specifies the vaporisation properties of the current material (saturation temperature and vapour pressure plus latent heat of vaporisation). FSEVAP FSTEN Lagrangian multi-phase subroutines COLLDT Activated from the Collision Model menu in panel Droplet Physical Models and Properties (tab Global Physical Models) or by command DCOLLISION. It specifies the method of calculating the droplet number density used for collision modelling in transient Lagrangian flow problems. COLLND DRAVRG 14-12 Version 4. It then specifies the speed of sound in the current material (for both the liquid and vapour phases) and the saturation vapour pressure. It specifies the method of detecting inter-droplet collisions in transient Lagrangian flow problems. It is activated from one of the following locations: (a) The Saturation Pressure menu in panel Cavitation Model or by command CAVPROPERTY. Activated from the Collision Model menu in panel Droplet Physical Models and Properties (tab Global Physical Models) or by command DCOLLISION. use command STENSION.02 . Activated from the Additional Properties menu in the Heavy Fluid Molecular Properties panel (Free Surface or Cavitation folders). It calculates values for surface tension coefficient and contact angle in free surface and cavitation problems. use command VAPORIZATION. It calculates the vaporization rate in problems involving mass transfer by evaporation across a free surface. It enables the user to define the heat transfer process between droplets and the surrounding carrier fluid in two-phase Lagrangian flow problems. Activated from the Momentum Transfer menu in panel Droplet Physical Models and Properties (tab Droplet Physical Models) or by command DRMOMENTUM.02 14-13 . It enables the user to calculate momentum transfer between droplets and the surrounding carrier fluid in two-phase Lagrangian flow problems. Lagrangian flow problems.Chapter 14 USER PROGRAMMING Description of UFILE Routines DRHEAT Activated from the Heat Transfer menu in panel Droplet Physical Models and Properties (tab Droplet Physical Models) or by command DRHEAT. This subroutine can also be used for specifying mass transfer between a droplet component and multiple scalars in the surrounding medium. Specifies a user-supplied droplet break-up model (see Chapter 10 of the Supplementary Notes volume) Activated from the Droplet User Subroutine (Lagrangian Multi-Phase) or by command DRUSER. use command DRCMPONENT. This is done by first selecting the component in the scroll list of the Droplet Properties tab and then typing the keyword User in the Evaporates to Scalar box. Activated from the Mass Transfer menu in panel Droplet Physical Models and Properties (tab Droplet Physical Models) or by command DRMASS. It is activated by selecting the Subroutine Usage button next to any of the properties displayed on the tab. In transient problems. Alternatively. Enables the user to specify any physical property appearing in panel Droplet Physical Models and Properties (tab Droplet Properties). and mass exchange between droplets and wall boundaries. It enables the user to define the mass transfer process between droplets and the surrounding carrier fluid in two-phase Lagrangian flow problems. heat. or by command DRPROPERTIES. the subroutine sets the initial conditions for any calculation time step at which parcels are released. Activated from the Droplet-Wall Interaction menu in panel Droplet Physical Models and Properties (tab Droplet Physical Models) or by command DRWALL. The subroutine enables the user to specify droplet initial conditions for two-phase. DRMAST DROBRK DROICO DROMOM DROPRO DROWBC Version 4. It enables the user to calculate momentum. It is activated from the main menu in the Drag Forces panel (Eulerian Multi-Phase folder) or by command EDRAG. It is activated by selecting User in the Options menu of the Film Initialization panel or by command LQFINITIAL. It is activated by selecting User in the Film Boundaries panel or by command LQFBC. The latter is used to derive the dispersed phase turbulence characteristics from those of the continuous phase. Specifies initial conditions for all liquid film variables at a given boundary region. It is activated from the Ct Model menu in the Turbulence Models panel (Multiphase Options tab) or by command ETURB. momentum and enthalpy equations for liquid films. LQFBCD LQFINI LQFPRO LQFSOR Eulerian multi-phase subroutines UEDRAG This subroutine is used in Eulerian multi-phase problems to calculate the total drag force. Modifies the source terms of the mass. It is activated by selecting User in the Stripping and Re-entrainment menu of the Film Controls panel or by command LFSTRIP. This subroutine is employed in Eulerian multi-phase problems to calculate the response coefficient C t . Note that the drag force per unit volume referred to above is supplied as an input variable since it is often a parameter in C t formulations. Specifies boundary conditions at liquid film inlets. per unit volume of the computational cell. It is activated by selecting User in the User Defined Source Term menu of the Film Controls panel or by command LFQSOR.USER PROGRAMMING Description of UFILE Routines Chapter 14 Liquid film subroutines FDBRK Specifies the method of calculating liquid film stripping by the carrier fluid. or by command LQFPROPERTY. UETURB 14-14 Version 4. Specifies liquid film physical properties or liquid film component partial pressures.02 . It is activated by selecting the Subroutine Usage button next to any of the properties displayed on the Film Properties tab (panel Film Physical Models and Properties). Alternatively. Chemical reaction subroutines COALC Specifies a user-supplied char combustion model in coal combustion cases (see Chapter 3. or by command NOX. or Fuel NOx menus in panel Emissions (Chemical Reactions folder). prompt or fuel NOx sources. “User Coding” in the Supplementary Notes volume) Specifies a user-supplied volatile evolution model in coal combustion cases (see Chapter 3. type command RRATE.Chapter 14 USER PROGRAMMING Description of UFILE Routines UEHEAT This subroutine is employed in Eulerian multi-phase problems to calculate the Nusselt number. It contains user coding for the calculation of thermal. COALV FULPRO PARUSR RATUSR REACFN Version 4. Alternatively. It specifies a user-supplied reaction rate for chemical reactions of any type. The subroutine is activated from the Interphase Heat Transfer panel (Eulerian Multi-Phase folder) or by command EHTRANSFER. Alternatively. Prompt NOx. “User Coding” in the Supplementary Notes volume) Specifies a user-supplied method of calculating turbulence effects in complex chemistry models (see Chapter 4. which in turn is used to compute the interphase heat transfer when solving for energy for either phase. type command IGNMODEL. Specifies a user-supplied particle component evolution model in coal combustion cases (see Chapter 3.02 14-15 . It can be activated in two ways: (a) From the Ignition Reaction Based On menu in panel Ignition (folder Chemical Reactions). The latter is then used in the calculation of the mean interface heat transfer coefficient. “User Coding” in the Supplementary Notes volume) Specifies user-defined fuel physical properties and chemical reaction parameters for use with the Shell ignition and knock models. (b) From the Knock Reaction Based On menu in panel Knock (folder Chemical Reactions). NOXUSR Activated by the Thermal NOx. type command KNOCK. “RATUSR User Subroutine” in the Supplementary Notes volume) Activated from the Rate Model menu in the Reaction System (Chemical Reactions) panel when option Combined/User is chosen as the current reaction model. Generates post-processing data at coupled boundaries.Explicit is selected from the Reference Frame Treatment menu. Alternatively. chemical species mass fractions can be calculated from user-prescribed algebraic relationships. use command MVGRID. In some circumstances. Alternatively. The old time level coordinates are available in the VCORN array and must be overwritten with new coordinates. e. UASI 14-16 Version 4. The subroutine specifies the cell vertex coordinates at a new time. rather than from finite-volume transport equations. Alternatively. The sample coding supplied describes a moving mesh that is linearly expanding and contracting between a reciprocating piston and a fixed cylinder head. activated from the Solution Method menu in panel Additional Scalars (Solution Controls > Equation Behavior sub-folder). use command SCPROPERTIES. SCALFN Rotating reference frame subroutines UOMEGA Calculates values of angular velocity (omega) for problems involving rotating reference frames. It is activated from panel Reaction System. The subroutine is called automatically in the Rotating Reference Frames panel if option Multiple Frames .02 . These algebraic relationships can be specified in this routine.g. the piston is driven by a rotating crank mechanism. It is activated by the User Option menu in the Rotating Reference Frames panel or by command SPIN. Specifies the time-varying offsets used in matching arbitrary sliding interface (ASI) boundaries. type command CRMODEL. stoichiometric relationships. Alternatively.USER PROGRAMMING Description of UFILE Routines Chapter 14 REACUL Specifies a user-supplied reaction rate for the Coupled Complex Chemistry model. use command MFRAME. having previously selected option User from the Reaction Rate Calculated by menu in panel Scheme Definition (folder Chemical Reactions). It is used in problems with multiple rotating frames of reference that are solved explicitly. It is called automatically if a model employing sliding events is defined using command EVSLIDE. UPOSTM Moving mesh subroutines NEWXYZ Activated by selecting Modules > Transient from the main pro-STAR menu to open the Advanced Transients dialog. and then selecting On in the Moving Grid Option menu. This is useful. “Inter-phase heat transfer term” in the Supplementary Notes volume). Mean temperatures and mass fractions for all fluid materials are made available through the parameter list. the transformation from a rotating reference frame. It is called automatically if a moving mesh model is defined using commands in the EVENTS module. It initialises flow field variables to user-specified values. if command MVGRID. During an initial field restart. Velocities in this system will differ from the velocities produced by the subroutine because of this transformation and. use command INITIAL. Generates parameters required for moving meshes. Activated by a button labelled Heat and Mass Transfer in the Miscellaneous Controls (Other Controls) panel. i. It modifies or supplies new wall functions for heat and mass transfer.02 14-17 . or by command HCOEFF.e. These values override any constant values also appearing in those panels. Alternatively.Chapter 14 USER PROGRAMMING Description of UFILE Routines UBINIT Specifies initial conditions for cells that are re-incorporated into the solution domain via an INCLUDE event.ON. UPARM Miscellaneous flow characterisation subroutines INITFI Activated from the Values menu in the Initialization panel (Liquids and Gases or Solids folders). in problems involving strong natural convection where the standard formulae for the transfer coefficients might be inaccurate. when that feature is active. Note that the subroutine returns velocities in a local coordinate system. STAR transforms them to a stationary global Cartesian system. One such example is included in the sample coding.EVENT. for example. Specifies user-supplied coefficients for a quasi-linear relationship between porous solid and fluid temperatures in problems involving conjugate heat transfer in porous media (see Chapter 16. It is called automatically if command EICOND is issued in a model employing such cells. the subroutine can also be used to selectively reset some of the variable values in the field. MODSWF PORHT2 Version 4.PROSTAR is issued. Alternatively. open the Advanced Transients dialog. use command TIME. for example. select option User in the Time Step Option menu of the Set Run Time Controls panel (Analysis Preparation/Running folder). It can be activated in two ways: (a) From the Prandtl(Enth). Alternatively. Alternatively. In this case. so your code must ensure that the time step lengths are such that the length of the load step is correct. the subroutine should supply special functions for calculating the turbulent Schmidt number of chemical species in multi-component mixing problems. in fire and smoke movement simulations that involve a large. concentrated heat source. Solution control subroutines DTSTEP Enables the user to specify a variable time step for transient. select option User in the Time Step Method menu of the Set Run Time Controls panel (Analysis Preparation/Running folder). or by typing command SCPROPERTIES. 14-18 Version 4.USER PROGRAMMING Description of UFILE Routines Chapter 14 VARPRT Enables specification of either a variable Prandtl number for enthalpy or a variable Schmidt number.02 . select the appropriate load step. (b) Via the Schmidt Number pop-up menu in the Binary Properties (Additional Scalars) panel. The subroutine can be used. It can be activated in three ways: (a) For single-transient cases. Note that STAR does not alter the number of time steps in a load step. single-transient or pseudo-transient simulations. type command COKE. The time step can be adjusted in terms of the number of PISO correctors and maximum Courant number. use command LSTEP. Alternatively. use command DELTIME (b) For pseudo-transient cases. and then click the User Flag button in front of the time step (Delta Time) box. (c) For transient cases. menu in panel Turbulence Models (Turbulence tab). use command DSCHEME. DEN ) EQUIVALENCE( UDAT11(003). VISM ) EQUIVALENCE( UDAT11(063). ICTID ) EQUIVALENCE( UDAT11(001). This subroutine may be called both at the beginning and at the end of every time step or iteration.000 INCLUDE ’comdb. VIST ) Version 4. (c) Calculation of lift and drag coefficients.CKNY.inc’ C COMMON/USR001/INTFLG(100) C INCLUDE ’usrdat. It can be used to vary the blending factor for higher-order discretisation schemes over the computational domain. For example: (a) Variable values at several monitoring locations can be written to user-designated output files for subsequent processing. Users wishing to inspect the contents of any other subroutine should start a pro-STAR session and then activate the User Subroutines dialog. ED ) EQUIVALENCE( UDAT11(006). V ) EQUIVALENCE( UDAT11(061). Alternatively. It performs special post-processing operations. T ) EQUIVALENCE( UDAT11(008). Sample Listing The listing for subroutine CONDUC is given below as an example of the default source code available in STAR-CD. (b) A bulk averaging scheme can be prescribed for selected flow variables and printed at specified intervals.00.inc’ DIMENSION SCALAR(50) EQUIVALENCE( UDAT12(001).Chapter 14 USER PROGRAMMING Sample Listing POSDAT Activated by the User subroutine button in the Analysis Output (Output Controls) panel or by command PRFIELD. TE ) EQUIVALENCE( UDAT11(009). as explained in “Subroutine Usage” on page 14-1. P ) EQUIVALENCE( UDAT11(007). The place from which it is called is distinguished by the value of parameter LEVEL (=1 — beginning. U ) EQUIVALENCE( UDAT11(060).CKNZ) C Conductivity C************************************************************************* C--------------------------------------------------------------------------* C STAR-CD VERSION 4. SCALAR(01) ) EQUIVALENCE( UDAT11(059).CKNX. CP ) EQUIVALENCE( UDAT11(002). W ) EQUIVALENCE( UDAT11(062).02 14-19 . C************************************************************************* SUBROUTINE CONDUC(CON. =2 — end) VARBLN Activated by the Blending Method pop-up menus in the Primary Variables panel (Differencing Schemes tab). IFLUTYP and DENDT are no longer present DENSIT 14-20 Version 4.CKNY.02 .EQ.Anisotropic conductivity in y-direction C CKNZ . User routine CAVPRO Difference Freedom to modify AL. C C ** Parameters to be returned to STAR: CON. freedom to modify the heavy/light density has been removed.2X and V4.00 user routines.11) CON=4.CKNZ C C----------------------------------------------------------------------C C Sample coding: To specify thermal conductivity for a group of C cells with cell table numbers 2 and 11 as a function C of temperature C C IF (ICTID. C C CON .Isotropic conductivity or MAX(CKNX. Note that STAR-CD V3. Z ) Chapter 14 C C----------------------------------------------------------------------C C This subroutine enables the user to specify thermal conductivity. AV.Anisotropic conductivity in z-direction C C C STAR calls this subroutine for cells and boundaries.2X user coding will work without any modification.2.CKNY.USER PROGRAMMING New Coding Practices EQUIVALENCE( UDAT11(067).Anisotropic conductivity in x-direction C CKNY .EQ.OR. X ) EQUIVALENCE( UDAT11(068). TSAT and HVAP has been removed For the Free Surface model. Y ) EQUIVALENCE( UDAT11(069).3+0.ICTID.2X / V3.1X common blocks / variable names should not be used.CKNX. The table below explains the differences between V3.001*T C-------------------------------------------------------------------------C RETURN END C New Coding Practices Most standard STAR-CD V3.CKNZ) if the C conductivity is anisotropic C CKNX . only the mixture Cp needs to be specified. V3. VOLCU. WFSI VOLF. COMMON /DRCOMP/ NDRCOM_max b/ The DEMUCO array needs to be dimensioned as DEMUCO(NDRCOM_max. FBSI KEYSUB T(1. lfc sv w svol af fl doma(nd)%sd(nsd)%irot t(ip) c(IP. LX S.00 are listed below.02 14-21 . WFCY. LCO. COCO.00 data item See material/and loop in posdat.f. see posdat. POSDAT SPECHT Data structure is different For the Free Surface model.FLUID test tells you whether you have a fluid or a solid. only the mixture viscosity needs to be specified. please consult the default source code for DROWBC supplied with the STAR-CD installation. Commonly used V3. COCU.2X data item KEY LQ. IFLUTYP is no longer present For the Free Surface model. doma(nd)%mattyp. SBSI WF. SB. ACB F.eq. VOLSI AC.IP) T(scalar index +1.2X data items that are now accessed differently in V4.scalar index).*) For more information. e. LSI. LCU. IP) Equivalent V4.Chapter 14 USER PROGRAMMING New Coding Practices DROWBC a/ The DRCOMP common block needs to be included to the source. COCY.f Version 4. FB. LCY. WFCU. IFLUTYP is no longer present VISMOL Users are advised to consult subroutine POSDAT to gain familiarity with STAR-CD’s new face-based data structure. COSI. VOLCY.g. they are not necessary for sequential runs.inc to user subroutines: IHPC — this is the local process number (1 ≤ IHPC ≤ NHPC) IHPC = 1 for a sequential analysis IHPC = 1 for the ‘master’ process in STAR HPC IHPC > 1 for the ‘slave’ process in STAR HPC Number of processes (NHPC = 1 for a sequential analysis) Number of fluid ‘halo’ cells on the local process Total number of ‘halo’ cells on the local process (fluid plus solid) NHPC NHHPC — — NTHHPC — 14-22 Version 4.ISTAT) IF (ISTAT.02 .NCOF CALL LIVCLL(I.USER PROGRAMMING User Coding in parallel runs Chapter 14 User Coding in parallel runs If user coding is present in a parallel run. it is possible that some of the required operations need access to flow field values that are distributed throughout the various computational domains. These routines should only be called if required. To aid diagnostics. NHPC > 1 if parallel run IF(NHPC. it is necessary to collect such values prior to manipulation and to do this.1) NLIVE=IGSUM(NLIVE) A synopsis of the available message passing-routines is given in Appendix E.ICELLEND. In such cases. the supplied coding needs to use special message passing routines. The example shown below is an extract from user subroutine NEWXYZ and it employs a parallel function called IGSUM to find the global number of active cell layers in an engine simulation problem. NLIVE=0 ICELL1=15904 ICELLEND=62209 NCOF=1029 DO I=ICELL1.1) NLIVE=NLIVE+1 ENDDO c.EQ. four variables are provided via file usrdat.GT. Chapter 15 PROGRAM OUTPUT Introduction Chapter 15 PROGRAM OUTPUT Run-time screen output from STAR provides a summary of the input specification for the problem being solved and also allows monitoring of the calculation progress. Version 4.e.02 15-1 . All listed data reflect the values stored in the problem (. The various checks and outputs which are specially activated from pro-STAR’s STAR GUIde environment (Output Controls folder) are described below. as follows: General Data This section provides general information on the problem at hand. steady or transient) The starting iteration number for the calculations The frequency of solution data and screen output The solution algorithm and linear equation solver selected The residual tolerance used for convergence tests The maximum number of iterations or time steps specified A sample output can be seen in Section A of Table 15-1. This is followed by a table of essential model data for checking that all important user-defined inputs are correct. apart from a core of information that is always produced. Introduction The amount of information displayed is largely up to the user. It is therefore important for users to understand this information and examine it regularly to ensure that • • the problem has been correctly set up. The table is divided into distinct sections. including: • • • • The case name Number of cells The model’s overall physical dimensions The run precision (single or double) This section of the table also summarises: • • • • • • The character of the flow (i. along with the permanent output.prob) file. the input summary begins with the STAR-CD version number and the date and time of the run. the calculations are proceeding satisfactorily. An echo of the input data provided by the user 2. Permanent Output The core-level screen information from STAR can be divided into two sections: 1. A display of analysis results and information on the progress of STAR calculations Input-data summary As can be seen in Table 15-1 on page 15-4. such as: • • • Radiation Free surface Run-specific system settings The sample output of Table 15-1. For each domain. User FORTRAN Coding This section of the table only appears when user-defined FORTRAN coding is active during the calculations. specific heat and conductivity. by tables of properties for solid domains such as density. including the turbulence model selected and the appropriate characteristic length The physical properties specified.02 . This can be seen in Table 15-1. The reference temperature. information is provided on any additional features that are active in the model.PROGRAM OUTPUT Permanent Output Chapter 15 Fluid Properties This section comprises one or more tables containing the properties of all fluid domains (streams) included in the model. initial field values and boundary conditions are also included here. such as density. solver tolerances. viscosity. Section C. the corresponding blending factors. Additional Features In this part of the table. specific heat. and conductivity The pressure/temperature reference locations for the domain The reference pressure and temperature (when appropriate) Any fixed boundary fluxes included in the model The specified initial field values The specified boundary conditions An example of the output for a multi-domain case appears in Table 15-1. sweep limits. residual normalising factors for each fluid and solid domain. The sample case presented in Table 15-1 does not use this option. indicates use of memory-based scratch files and platform-specific solver optimization. in the case of solid-fluid heat transfer problems. Solid Properties The fluid domain tables are followed. For transient PISO runs the printout of relaxation factors is suppressed as irrelevant. This shows data for two fluid domains with different physical properties. A typical printout of the above 15-2 Version 4. except for the pressure correction relaxation factor. type of differencing scheme used. Section D. Solution Parameters This last section of the table deals with the settings for the control parameters used by the numerical algorithm. such as • • • • • • relaxation factors. Section B. the information supplied includes: • • • • • • • The variables calculated. Printout of Field Values The printout of field values for the solution variables is optional and. Section E.). Output of additional data is activated by various options in the “Monitor Numeric Behaviour” STAR GUIde panel. In steady-state runs. pressure. The . stabilisation of the values of flow field variables at the monitoring location. 2. The left-hand section contains the global absolute residual histories for each group of transport equation solved (momentum. Note that velocity component data at the flow field’s extrema are given in the local coordinate system. 1). oscillations can be observed. Version 4.run) file. These can be ignored as long as the overall residual levels are reduced over a reasonable number of iterations. which are always stored in the global Cartesian coordinate system. etc. satisfactory progress of the calculations should show • • a steady reduction in the global absolute residuals from iteration to iteration. residuals do not always decrease from iteration to iteration and. There is also a similar “Print Cell Range” section in the transient-problem version of this panel (“Post tab”). This output appears on the screen during an interactive session and is also saved in the run-time output (. in some cases.ccm)”. Optional Output All additional outputs are optional and. Table 15-4 on page 15-8 shows typical information appearing in this file (in this case up to and including data for iteration no. However. mass. 1.02 15-3 .info file.run file also contains a reminder to the effect that warning messages have been produced. turbulent viscosity. turbulence.Chapter 15 PROGRAM OUTPUT Printout of Field Values parameters can be seen in Table 15-1. This is in contrast to the data described in Chapter 17.) at a pre-defined monitoring location in domain no. follows the analysis history output. Run-time output The run-time output that provides information on the progress of the calculations at each iteration or time step can be seen in Table 15-2 on page 15-6 and is arranged in two sections: 1. “Data repository file (. The output quantity and frequency is left up to the user and may be set using various options in the “Analysis Output” STAR GUIde panel — see the “Print Cell Range” section for steady-state problems. Information on total CPU and elapsed times is also given. etc. if requested. The right-hand section contains values of the corresponding dependent variables (velocity magnitude. An example of such a printout can be seen in Table 15-3 on page 15-7. will appear in the . Any warning messages generated during the course of the calculations are stored in the run-time optional output (. if present.info) file and should be inspected by the user separately. .000E+00 in C... Max = 0... => U....... OF ITERATIONS ...... => IDEAL GAS: MOLW = 2.33 | | => cappa=0....... => EVERY 10 ITERATIONS | | SOLUTION PROCEDURE .......0E-02 | | MESH QUALITY . C_3=1...........000E+00 | | Reg.. => 100 | | RESTART DATA . => | | PRESSURE REF. distribution..... Pr_eps=1...... => 1... => | | Reg... => WILL BE PRINTED ON FILE........ => PREF = 1.. P.. V...PROBLEM SPECIFICATION SUMMARY ---------------------------........... | | Proprietary data --.000E+00 Om = 0..44...... => 192 | | MESH DIMENSIONS XMIN XMAX YMIN YMAX ZMIN ZMAX | | (IN METRES) ....000E+00 W = 0.. => CONSTANT RHO = 1.. => WILL NOT BE EMPLOYED | | DATA DUMP (FILE....0E+00 0....... => SIMPLE | | RESIDUAL TOLERANCE . NO.. => WILL BE PRINTED | | LIN.... 2 Constant piezomet........ | |-------------------------------------------------------------------------------------------| |-> DOMAIN 1: FLUID ------------------------------------------------------------------| |-------------------------------------------------------------------------------------------| | SOLVE ...Sys... Pr_k=1....000 | | THERMOFLUIDS ANALYSIS CODE | | Operating System: Linux | | Stardate: 6-DEC-2005 Startime: 14:32:39 | |-------------------------------------------| |-----------------------------------------------------------| | STAR Copyright (C) 1988-2005...... | | or duplication is prohibited...Sys. SOLVER ...In.... pressure: P = 0............. P. C_2=1.810E-05 Pas | | | | INITIAL FIELD VALUES .....00.. => TURBULENT INCOMPRESSIBLE | | TURBULENCE MODEL ...000E-03 | | Reg............ | | => 2..... Max = 1... 1 Inlet: U = 0.00 (CVs: 0.... | |-----------------------------------------------------------| |-------------------------------------------------------------------------------------------| | ---------------------------.......000E+00 | | TI = 5. EQU.. C_1=1......00 (CVs: 43.ccm) . All rights reserved...00E-03 | | MAX.0E+00 | | => Tur............. CELL .........000E-03 | | Reg..ccm | | SURFACE DATA .. => PREF = 1.... => Aver = 1. Computational Dynamics Ltd....000E+05 Pa | | DENSITY ....000E+01 W = 0.000E+05 Pa | | DENSITY . C_4=-0.......... 44) | | Non-orthogonality (deg)... => u v w p | | => 0... 5 Symmetry plane | |-------------------------------------------------------------------------------------------| |-> DOMAIN 2: FLUID ------------------------------------------------------------------| |-------------------------------------------------------------------------------------------| | SOLVE ........00.00...000E+00 in C.......| |-------------------------------------------------------------------------------------------| | CASE TITLE .0E+00 0... => WILL BE SAVED ON out....0E+00 5......90 | | REFERENCE PRESSURE . => HIGH RE K-EPS MODEL | | CONSTANTS ..................92.. Choleski precond.. | | FLUID FLOW ... => CONSTANT MU = 1........ 1 | | TI = 5. => Single | | STEADY ANALYSIS ........ ALG. ED.. => Conjugate gradient with Incompl........Sc.... => 145 | | REFERENCE PRESSURE ..000E-02 TLS = 5...000E+00 Om = 0...... => 0.....0E-01 0... => C_mu=0.0E+00 8..... 1 | | Elog = 9........ => Aver = 0.....6E-02 1.891E+01 | | MOLECULAR VISCOSITY ........0E-01 | | BOUNDARY CONDITIONS ... => | | Expansion factor ..02 .......info | | FIELD DATA .=> START FROM ITERATION = 0 | | INITIALISATION .. => WILL NOT BE SAVED | | CONVERGENCE DATA ..419...09......0E+00 0.........44....PROGRAM OUTPUT Example Output Chapter 15 Example Output Table 15-1: |-------------------------------------------| | STAR-CD VERSION 4. 0 Wall: U = 0..0E-01 0.. V...000E+03 kg/m3 | A B B 15-4 Version 4.....Unauthorized use. Len... 0) | | RUN PRECISION ......00.219.............000E+00 V = 5.000E-02 TLS = 5. => LAMINAR INCOMPRESSIBLE | | TURBULENCE MODEL ..... | | FLUID FLOW ....... => | | NUMBER OF CELLS . TE..0E+00 6...000E+00 V = 0.......... Pr=0. => U... . 0 Wall: U = 0. 5 Symmetry plane | |-------------------------------------------------------------------------------------------| |-> ADDITIONAL FEATURES USED --------------------------------------------------------------| |-------------------------------------------------------------------------------------------| | PLUG AND PLAY | | RAMFILES OPTION ENABLED | | TURBO OPTION ENABLED | |-------------------------------------------------------------------------------------------| |-> SOLUTION CONTROL PARAMETERS | |-------------------------------------------------------------------------------------------| | VARIABLE | Mome Mass Turb ---| |-------------------------------------------------------------------------------------------| | RELA......Sys. 1 | | Reg... => | | Reg..000E+00 Om = 0.0E+00 | | BOUNDARY CONDITIONS .. | UD CD UD ---| | DSCH. TOL..Chapter 15 PROGRAM OUTPUT Example Output | MOLECULAR VISCOSITY .000E+03 kg/m3 | | SPECIFIC HEAT ... 5 Symmetry plane | |-------------------------------------------------------------------------------------------| |-> DOMAIN 3: SOLID ------------------------------------------------------------------| |-------------------------------------------------------------------------------------------| | SOLVE ....000E+00 Om = 0...000E+00 | | Reg.00 | | BOUNDARY CONDITIONS .000E-01 ---| | SWEEP LIM..000E-01 7... => URF = 1...800E+02 W/mK | | INITIAL FIELD VALUES ..0E+00 0....800E+02 J/kgK | | CONDUCTIVITY .. 1 | | Elog = 9..000E-01 ---| | DIFF.. => CONSTANT rho = 9. 0 Wall: U = 0..000E+00 V = 0.......000E+00 V = 0....000E+00 V = 1.. 1 | | Reg... | 1.000E+00 1... => T | | REFERENCE TEMPERATURE ..000E+00 W = 0..... | 0. => u v w p | | => 0..000E-01 W = 0...000E+00 in C..000E+00 in C..000E-03 Pas | | | | INITIAL FIELD VALUES ...... IN SOLID .730E+02 K | | DENSITY ..000E-01 2.. FACT...000E+00 Om = 0.000E+00 W = 0......... | 7.. => | | Reg...0E+00 0.000E-01 5...Sys. FAC. 4 Outlet: Flow split = 1..... 3 Inlet: U = 0.. => CONSTANT k = 3... FAC.Sys...0E+00 0......000E+00 in C.... | 100 1000 100 ---| |-------------------------------------------------------------------------------------------| C D E Version 4...... => T | | => 2.02 15-5 ...... => CONSTANT MU = 1..000E-02 1...000E+00 ---| | SOLV... SCH......9E+02 | | RELAX.. => TREF = 2...000E+00 | | Reg.000E+00 0..... => CONSTANT c = 3. 56E-03 1.50E+00 2.95E-04 ----4.78E-01 2.40E-02 -12 1.94E+01 4.22E-02 ----5.23E-02 ----5.85E-02 ----5.39E-02 -13 7.56E-04 2.50E-02 9.13E-02 3.90E-01 2.01E-03 6.05E-05 1.83E-04 3.06E-04 ----4.25E-04 4.25E+01-3.36E-05 8.78E-04 ----4.11E+01-1.22E-03 1.33E-02 7.25E-05 ----4.18E-04 1.25E-04 ----4.36E-01 3.98E-01 2.78E-02 1.46E+00 2.15E-03 3.06E+01-5.41E-03 1.54E-03 1.32E-02 -7 4.44E+00 2.38E-02 -15 3.38E-02 -17 2.15E-03 1.48E-02 -4 1.39E-03 7.98E+01-1.93E+01 1.CONVERGENCE CRITERION SATISFIED 15-6 Version 4.10E-02 5.01E-03 8.33E-03 3.09E-04 2.60E-03 -2 6.04E+00 8.32E+01-4.info ************************************************** *** CALCULATIONS TERMINATED .38E+00 2.36E-02 3.45E+00 2.20E-01 1.05E-03 -3 2.26E-02 4.41E-02 -10 1.39E-03 1.92E+01 1.38E-02 -19 1.96E+01 2.15E+00 1.69E-04 ----4.31E-03 ----5.66E-03 1.07E-05 1.98E-01 ----5.38E-02 -8 3.80E-06 ----4.78E-01 2.46E+01 4.92E+01 1.62E+00 2.38E-02 -20 9.30E-03 ----5.53E-06 ----4.52E-05 1.38E-02 -18 1.18E+01-2.40E-02 -11 1.90E-03 9.79E-03 ----4.37E-03 5.00E+00 9.38E-02 -16 2.36E-04 5.37E-05 ----4.95E-02 1.56E-01 ----5.28E-05 ----4.69E-01 2.93E+01 9.94E-02 -5 8.00E+00 1.11E-01 2.92E+01 1.23E-04 ----4.08E+00 2.19E-02 -6 6.73E-03 3.40E-02 -9 2.FIELD VALUES AT MONITORING No Mome Mass Turb ----Vel Pres TurVis -1 1.46E-03 2.02E-03 2.11E-02 2.29E+00 2. I--------------.92E+01 1.81E-04 2.32E+00 2.92E+01 1.PROGRAM OUTPUT Example Output Chapter 15 Table 15-2: Iter.02 .01E+01-4.39E-02 -14 5.00E-03 6.38E+01-2.12E-03 ----4.38E-02 -&&&& --------------------------------------------------------------------------------------------------------------------------POINT ------------------------63 ----------I ------------------------------------------------- ************************************************** * THERE ARE WARNINGS IN FILE out.48E-02 ----5.93E+01 1.93E+00 2.GLOBAL ABSOLUTE RESIDUAL ------------------I I-------.56E-03 7.64E-02 1.35E-01 2.38E-02 -21 7.93E+01 1.34E+00 2.22E-04 5.72E-05 ----4.92E+01 1.01E-01 ----5.66E+01 6.38E-02 -23 4.38E-02 -22 5.86E-03 1.48E-03 2.94E+01 6.45E+00 1.41E+00 2. 314E+01 3.000E+00 9.939E+03 51 2.500E-02 2.000E+00 0.849E+02 6.FIELD VALUES AT ITERATION NO CELL NO 1 11 21 31 41 51 61 71 81 91 101 111 121 131 141 151 161 171 181 191 U VEL -3.930E+02 2.000E+00 0.Chapter 15 PROGRAM OUTPUT Example Output Table 15-3: I-------------------------------------------.000E+00 END OF EXECUTION .000E+00 0.000E+03 1.000E+00 I--------------------------------------------| Wall data at iteration No Region No: 0 Cell No Y-PLUS 49 2.172E+04 1.930E+02 2.403E-03 8.187E+00 9.000E+00 0.369E+02 4.000E+00 0.000E+00 0.000E-01 1.500E-02 2.818E-03 8.000E+00 0.001E-01 PRESS 1.000E+00 0.000E+00 -1.000E+00 134 0.000E+00 0.000E+00 0.500E-02 2.276E-05 2.000E+00 0.000E+00 0.047E+01 3.172E+04 1.000E+00 0.000E+00 0.000E+03 9.797E-03 TUR EN 8.000E+00 DISSI 8.930E+02 2.000E+00 0.635E+01 6.000E+00 0.930E+02 2.000E+00 0.140E+03 62 3.935E+01 0.172E+04 1.930E+02 2.289E+01 3.172E+04 1.000E+03 9.124E+01 3.000E+00 144 0.000E+00 130 0.465E+00 6.700E-02 -4.000E+00 131 0.000E+00 96 0.930E+02 2.000E+00 0.000E+00 135 0.000E+00 0.241E-03 -9.000E+00 80 0.187E+00 1.500E-02 0.000E+03 9.930E+02 2.000E+00 0.000E+00 0.500E-02 2.000E+00 0.000E+03 1.097E-05 6.000E+00 0.274E+01 3.930E+02 2.966E-02 1.021E-02 -2.930E+02 2.000E+00 0.000E+03 9.172E+04 1.500E-02 2.172E+04 1.000E+00 141 0.500E-02 2.172E+04 1.172E+04 1.454E-05 6.139E+03 63 3.500E-02 2.930E+02 2.500E-02 2.172E+04 1.075E+03 54 3.000E+00 0.137E+03 64 3.999E+03 52 3.310E+01 1.930E+02 2.000E+00 0.500E-02 2.000E+03 1.000E+00 0.000E+00 0.000E+00 0.000E+00 0.000E+00 140 0.172E+04 1.000E+00 0.989E+01 4.000E+00 0.172E+04 1.116E+01 1.500E-02 2.000E+00 0.930E+02 2.000E+00 0.172E+04 1.000E+00 0.311E+01 3.712E-05 2.000E+00 0.000E+00 0.172E+04 1.825E-03 9.000E+00 0.000E+00 112 0.500E-02 2.772E-02 0.187E+00 1.000E+00 0.000E+00 0.000E+00 0.000E+00 0.930E+02 2.275E-02 2.187E+00 1.858E+03 50 2.000E+00 0.300E+01 3.000E+00 0.930E+02 2.000E+00 138 0.000E+00 0.000E+00 133 0.172E+04 1.500E-02 2.222E+00 1.172E+04 1.930E+02 2.737E-03 -1.000E+00 0.043E+03 53 3.578E+00 4.026E+01 5.000E+00 0.329E+00 3.000E+00 0.930E+02 2.892E-03 -4.000E+00 0.000E+00 0.541E-06 1.718E+00 5.500E-02 2.000E+00 0.000E+00 0.930E+02 2.140E+03 61 3.000E+00 0.000E+00 0.000E+00 0.930E+02 2.000E+00 0.000E+00 HTRAN 3.311E+01 3.136E+03 59 3.000E+03 VISCO 9.000E+00 0.000E+03 9.000E+03 1.000E+00 0.000E+00 137 0.181E+01 3.000E+00 0.930E+02 2.000E+00 0.500E-02 2.500E-02 2.000E+00 0.098E+03 55 3.000E+00 0.500E-02 2.187E+00 1.000E+00 0.500E-02 2.000E+00 0.139E+03 60 3.500E-02 2.000E+00 0.610E+01 3.000E+00 0.172E+04 1.007E+01 5.125E+03 57 3.004E+02 2.930E+02 2.000E+00 0.000E+00 142 0.500E-02 2.708E+02 0.619E-02 -2.500E-02 2.000E+00 0.930E+02 2.395E-03 -9.000E+00 0.000E+00 0.000E+00 0.000E+00 0.854E-02 -5.000E+00 0.132E+03 58 3.987E-03 9.500E-02 2.000E+00 0.000E+00 0.546E+00 1.000E+00 0.114E+03 56 3.000E+00 3.172E+04 HFLUX 0.313E+01 3.673E+02 2.223E+01 0.000E+00 0.000E+00 0.000E+00 0.000E+00 113 0.000E+00 0.134E-05 V VEL 5.015E+01 4.187E+00 1.001E-01 1.000E+00 0.930E+02 2.172E+04 1.930E+02 2.000E+00 0.930E+02 0.000E+00 0.000E+03 1.000E+00 136 0.500E-02 2.172E+04 1.930E+02 2.500E-02 2.000E+00 0.000E+00 0.000E+00 0.000E+00 0.000E+00 0.337E+01 1.000E+00 81 0.000E+00 65 0.000E+00 139 0.930E+02 2.697E-03 -1.000E+00 0.000E+03 1.500E-02 2.000E+00 0.000E+00 0.001E-01 1.930E+02 2.000E+00 0.172E+04 1.172E+04 1.930E+02 2.814E-02 -5.172E+04 1.500E-02 2.675E-06 -1.000E-01 1.697E+00 9.223E+01 3.000E+00 0.500E-02 2.994E-02 9.000E+00 132 0.000E+03 1.930E+02 2.026E-04 -9.000E+00 23 |--------------------------------------------I NORM DIST 2.930E+02 2.980E+00 0.500E-02 2.000E+00 0.775E-03 2.550E+02 1.02 15-7 .000E+00 0.172E+04 1.000E+00 97 0.381E-02 0.000E+00 0.36 Elapsed time is 0.038E+00 1.500E-02 2.930E+02 2.000E+00 0.000E+00 WALL TEMP 2.500E-02 2.314E+01 3.000E+00 143 0.92 Version 4.000E+00 0.000E+00 0.187E+00 1.930E+02 2.000E+00 0.500E-02 2.018E+01 5.500E-02 2.000E+00 0.313E+01 3.239E-02 -6.135E+03 129 0.253E+01 3.STAR CPU time is 0.000E+00 128 0.000E+00 23--------------------------------------------I DENSI 1.000E+01 5.000E+00 0.306E+01 3.172E+04 1.980E+02 5.000E+00 0.000E+00 0. 1867E+00 Tvav 2.mass transfer from dispersed phase (droplets) to continuous phase.0000E+00 5.9209E-01 0.0000E+00 4 OUTLET 0. kg/s FDIFF .sum of absolute mass sources RES0 .0000E+00 VMAGmax 6.8710E+00 1.9212E-02 EPSmax 2.total flow in through partial cyclic boundaries. kg/s MSDRO . UMOM have reached round-off error limit in iteration 1 and trying to reduce them further can result in the solver divergence. 2 is *** Reduction of solution matrix bandwidth enabled *** ______________________________MEANING OF PRINTOUT QUANTITIES________________________________________ ---NOMENCLATURE (mass balance) ------FVIN .0000E+00 1.9337E-01 0. kg/s FLOUT .02 .9233E+00 6.9300E+02 TKEvav 1. kg/s FVOUT .000 | | THERMOFLUIDS ANALYSIS CODE | | Operating System: Linux | | Stardate: 6-DEC-2005 Startime: 14:32:39 | |-------------------------------------------| CASE NAME : out *** Warning: Molecular weight of material in domain set to 28. FDIFF TOTAL_FLOW_IN TOTAL_FLOW_OUT MSDRO (FVIN) (FPIN ) (FLOUT) (FVOUT) (FPOUT) 1 1 1.total flow out through outflow boundaries. ______________________________BALANCE DATA________________________________________________ DOMAINWISE MASS BALANCE (kg/s) MAT.0000E+00 0.5014E+01 Field Volume-Averages: Pvav RHOvav 2.total flow in through pressure.0000E+00 1.0000E+00 0.0000E+00 0. kg/s FLINJ .1391E+00 3.total flow out through pressure.total flow out through outlet boundaries. TYPE FLOW-IN(kg/s) FLOW-OUT(kg/s) 1 INLET 5.9337E-01 0.2811E-03 5. kg/s FPOUT .mass balance kg/s SUM .00. kg/s SDRDT .2349E+01 VMAGmin 3. Because of this further iterating is stopped.0000E+00 0.5615E+00 TKEmin 3.0000E+00 1.1867E+00 RHOmin 1.0000E+00 1.6307E+02 EPSmin 1. kg/s FPIN .9337E-01 5.3236E-01 Tmax 2.2337E+01 Umin Vmin -2.9300E+02 RHOmax 1. NO.stagnation.5077E+00 Pmin 2.total flow out through partial cyclic boundaries.0000E+00 2 PRESSURE 0.0000E+00 0.stagnation. kg/s FCYIN .5014E+01 Pmax 5.96.starting residual in the solver ITERATION NUMBER = 1 -------------------------*** Warning: Residuals in eq.mass accummulation by volume change in time.free-stream and transient-wave boundaries.0000E+00 0.3542E+00 EPSvav 2.mass accummulation by density change in time.9209E-01 2 1 0.9300E+02 Tmin 2.0000E+00 -----------.1867E+00 Field Mass-Averages: Wmax 0.PROGRAM OUTPUT Example Output Chapter 15 Table 15-4: |-------------------------------------------| | STAR-CD VERSION 4.mass injection.free-stream and transient-wave boundaries.0000E+00 5.0000E+00 Wmin 0.sum of mass sources RESP .0000E+00 5.0000E+00 0. kg/s FCYOT .total flow in through inlet boundaries. kg/s SDVDT .2631E+01 15-8 Version 4.BOUNDARY REGIONWISE -----------REGION NO. PHASE NO.0000E+00 ______________________________FIELD DATA_________________________________________________ *** FOR FLUID STREAM *** 1 Field Extrema: Umax Vmax 4.2318E-01 TKEmax 6.9209E-01 3 INLET 1.0000E+00 1. 0000E+00 EPSvav 0.02 15-9 .0000E+00 VMAGmax Pmax 1.0000E+03 Field Mass-Averages: Pmav RHOmav -1.9300E+02 Tmin 2.0000E+00 VMAGmin Pmin 5.9300E+02.8799E-02 -2.3542E+00 EPSmav 2.4465E-02 1.9300E+02 TKEmav 0.0000E+03 RHOmin 1.0000E-03 *** FOR FLUID STREAM *** Field Extrema: Umax Vmax 1. Tmin = 2.9300E+02 Field Solver information: NSU = 1 NSV = 2 NSW = 0 NSP = 14 NSTE = 1 NSED = 1 NST = 0 CPU time is 0.0000E+00 Tmav 2.5644E-01 Umin Vmin -7.0000E-03 2 TKE 1.8710E+00 RHOmav 1.0000E+00 EPSmav 0.0000E+00 8.5644E-01 0.0000E+00 TKE 0.0000E+00 EPSmax 0.0000E+00 Tmax 2.7720E-02 Field Volume-Averages: Pvav RHOvav -1.1867E+00 Tmav 2.0000E+00 Wmin 0.9300E+02.4449E-02 1.7495E-02 TKEmax 0.2631E+01 Field Totals: Mass Volume 9.9300E+02 TKEvav 0.13 Elapsed time is 0.4465E-02 1.4939E-03 8. Tvav = 2.0000E+00 EPSmin 0.0000E+00 EPS 0.2857E-02 EPS 2.0000E+03 Tvav 2.33 __________________________________________________________________________________________ Version 4.3840E-03 5.0000E+00 TKEmin 0.0000E+00 *** FOR SOLID domain *** 3 Temperature data: Tmax = 2.0000E+03 Field Totals: Mass Volume 8.9300E+02 RHOmax 1.9300E+02 TKEmav 1.1485E-01 Wmax 0.Chapter 15 PROGRAM OUTPUT Example Output Pmav 2. . The file itself may be edited with any suitable text editor to add/modify/delete any particular abbreviation. panel size and location (see “Panel definition files” on page 16-5) and ‘favourite’ panels (see “Panel Version 4.Prostar. Set-up Files These files are read automatically as part of the pro-STAR start-up process and are used in creating a suitable pro-STAR environment for the problem in hand. On Unix systems. The files have standard names. This provides a convenient way of setting up (initialising) pro-STAR in a standard way (regarding. 2. and are located in a directory chosen by the user. may be used in all subsequent pro-STAR sessions. 3. as needed.02 16-1 . for example. Some pro-STAR commands are in fact best used from within the PROINIT file. “pro-STAR environment variables”). The command group comes into action every time an existing ‘abbreviation’ is typed in the I/O window. plot type. PROINIT — contains pro-STAR commands that are read and executed as the first action in the current session. simply by associating them with an abbreviation name. This facility replaces settings previously made through environmental variables. The choice of which ones to use is largely a matter of user preference and the requirements of the model being built.) every time a session begins. For example: (a) Command OPANEL — typically used to open a set of tools (standard pro-STAR GUI dialogs or user-defined panels) that the user wants on screen at the start of every new session. File PRODEFS stores all current abbreviation definitions and. The available set-up files are as follows: 1. viewing angle. once created. PRODEFS — this file is created automatically if the *ABBREVIATE command is used during the session. etc. given below.Defaults — a hidden system file containing definitions of function keys (see “Function Keys” on page 16-9). the path to this directory is stored in an environment variable (STARUSR) specified outside pro-STAR using the appropriate Unix environment setup command (see Chapter 17. *ABBREVIATE enables one or more frequently used commands and their parameters to be joined together and executed in sequence. . (b) Command SETFEATURE — reports or changes the byte ordering format of binary files to suit machines such as the Compaq Alpha range.Chapter 16 PRO-STAR CUSTOMISATION Set-up Files Chapter 16 pro-STAR CUSTOMISATION pro-STAR provides four means by which users can customise the way they work with the program: • • • • Set-up files Panels Macros Function keys All are geared towards making problem data input faster and more flexible and can be used in combination with each other. If the set-up file directory is not defined through STARUSR. Panels are often employed to facilitate the use of Macros.PRO-STAR CUSTOMISATION Panels Chapter 16 navigation system” on page 2-40). Once this is done. New panels are created by entering a name in the text box of the Define Panel dialog box and then clicking on the New action button. or selecting the name in the list and then clicking on the Open action button. This results in the panel name being added to the list above the text box. 16-2 Version 4. Any of the above actions will display a panel such as the one shown below. Panels Panels are user-definable tools capable of simplifying the use of pro-STAR operations that are either not available in the existing GUI menus and dialog boxes or require additional functionality. Panel creation Panels can be created or modified by choosing Panels > Define Panel from the main menu bar to display the Define Panel dialog box shown below.02 . or clicking on Panels in the main menu bar and selecting the panel name from the drop-down list. which are groups of commands that are saved in a separate file (see “Macros” on page 16-6). pro-STAR creates default set-up files automatically in your current working directory. the panel itself can be opened by • • • double-clicking on its name in the list. Macros can be assigned to Panel buttons so that a large number of commands can be executed simply by clicking such a button. Users may also specify menus for panels by selecting File > Menus from the panel’s menu bar.Chapter 16 PRO-STAR CUSTOMISATION Panels Once the new panel has been opened. a single menu called User 1 is defined containing a single menu item called Replot which executes command REPLOT. where one can define up to six menus. their names and the pro-STAR commands that will be executed upon selecting a particular menu item. The above dialog box allows definition of the number and layout of the panel buttons (a maximum of 100). This opens the Define User Menus dialog box. By default. shown below.02 16-3 . the user can specify its layout and define its buttons and menu items. Version 4. The Panel Layout dialog box can be opened by selecting File > Layout from the panel’s menu bar. change them to solid cells and then plot the mesh. Example 2 Select a range of fluid cells by drawing a polygon around them. The following three examples illustrate the way in which frequently repeated operations may be simplified by assigning them to panel buttons: Example 1 Select a number of cells with the screen cursor and then refine them by a factor of 2 in all directions. Assign to option button CZMOD. A button’s definition is the pro-STAR command(s) that will be executed when the button is pushed.02 . 16-4 Version 4.PRO-STAR CUSTOMISATION Panels Chapter 16 Panel button names and definitions are assigned by first selecting a button. and then entering a new name or definition into the appropriate text box. Assign to option button CCREF. Note that selecting File > Reload from the panel’s menu bar will cancel out any changes made to the panel definition since it was last saved. but will not execute the button function. This sequence will set the newly selected panel button as the active button. The file location depends on its name. If the name entered was prefixed with the letter L or G (note that a space must be typed after each letter). To select a button without executing the corresponding button definition. move the mouse pointer clear of the button and then release the mouse button. which allows entry of local and global directory names in the corresponding text boxes. Version 4.PNL. On Unix systems. Assign to option button VCOOR2. the file will be placed in directory PANEL_LOCAL or PANEL_GLOBAL. This file is created using the panel name specified by the user in the Define Panel dialog box and the suffix . otherwise it will be put in your current working directory. the local and global directory names are stored in environment variables that can be set outside pro-STAR using the appropriate Unix environment setup command (see Chapter 17. This displays the Set Environment dialog box shown below. Next. “pro-STAR environment variables”).02 16-5 .Chapter 16 PRO-STAR CUSTOMISATION Panels Example 3 Display vertex coordinates in local coordinate system 2 by pointing at the required vertex with the cursor. The environment variables can also be set within pro-STAR by selecting Panels > Environment from the main menu bar. Panel definition files A panel’s button and menu settings as well as its size and location are saved in a panel definition file when File > Save is selected from the panel’s menu bar. move the mouse pointer to the button and press (but do not release!) the mouse button. The Copy button creates new panels by copying an existing panel definition file to another file whose name must be typed in the text box.02 .PRO-STAR CUSTOMISATION Macros Chapter 16 Command: SETENV Note that a list of available panels can be viewed by opening the Define Panel dialog box. Panels found in your current working directory are shown in the list with a ‘. as described in “Panel creation” on page 16-2. as follows: • The Re-Scan button recreates the list of available panels. respectively.’ before the panel name. The constituent commands must be stored in a special file. In addition to the panel definition file. The Delete button allows you to remove panels from the list but does not delete the corresponding definition files. Definitions stored there have priority over the size and location information stored in the panel definition file. a panel’s size and location are also saved in a hidden system file called . Once added to the list. Panel manipulation The Define Panel dialog box provides additional facilities for manipulating panels. The Rename button changes the name of a panel definition file to another name typed in the text box.Prostar. identified by a ‘. PANEL but this command is more typically issued from within the PROINIT set-up file (see “Set-up Files” on page 16-1). The latter can only be deleted outside pro-STAR by using the appropriate operating system command. This enables you to override such information if the panels are located in a directory for which you do not have write permission. Note that panels can also be opened from the pro-STAR input/output window by typing OPANEL. Those that were removed from the list will re-appear.Defaults (see “Set-up Files” on page 16-1). a panel can be opened in a number of ways.MAC’ extension and included within 16-6 Version 4. • • • Macros A macro is a set of user-defined commands that can be executed at any stage of the pro-STAR session. Any panel definitions found in the directories specified by the PANEL_LOCAL and PANEL_GLOBAL variables are shown in the list with an L or G prefix before the panel name. while those created via the New button but never saved will disappear. Clicking the Open or New button in the Define Macro box opens a macro editor to display the macro file(s) that has been selected in the macro list (or a blank sheet for new macros). The user can then type in the required pro-STAR commands or amend existing ones.’ in front of the macro name. as shown below. The Define Macro box. “pro-STAR environment variables”). supply required data or to click an appropriate menu item with the mouse.02 16-7 . by highlighting them in the list with the mouse and then clicking the Open button. Macros can be created. This displays the Set Environment dialog box which allows entry of local and global macro directory names in the corresponding text boxes. or a pre-defined global macro directory. pro-STAR looks for macro files in three places. As with panel directories. copied. by double-clicking its name in the macro list. The name of a new macro must be typed in the text box. Version 4. shown below. is opened by choosing Panels > Define Macro from the main menu bar. An existing macro can be selected and displayed. the local and global directory names are stored in environment variables MACRO_LOCAL and MACRO_GLOBAL that can be set outside pro-STAR using the appropriate Unix environment setup command (see Chapter 17. The environment variables can also be set within pro-STAR by selecting Panels > Environment from the main menu bar. Those found in the directories specified by the MACRO_LOCAL and MACRO_GLOBAL environment variables are shown with an L or G prefix before the macro name. Macros found in the user’s current working directory are shown in the list with a ‘. renamed. Several macros can be displayed simultaneously in multiple windows. and deleted in the Define Macro dialog box in the same way that panels are in the Define Panel dialog box. Command PROMPT. or a pre-defined local macro directory. respectively.Chapter 16 PRO-STAR CUSTOMISATION Macros • • • the current working directory. which displays messages in the area underneath the plotting window (see “Main window” on page 2-15) is particularly useful inside a macro as it can prompt the user to. say. Both strings are typed in the dialog box shown below: 16-8 Version 4. Edit (a) Find — find a character string typed in the dialog box shown below: (b) (c) (d) (e) Mark Selection — mark the selected characters for subsequent searches Find Selection — find the selected characters in the macro body Find Again — repeatedly find the selected characters Replace — find a character string and replace it with another string. File (a) (b) (c) (d) (e) Open — open another macro Save — save the current changes Save As — save the current changes to a different macro file Clear All — clear the editor window Quit — terminate the editing session 2.PRO-STAR CUSTOMISATION Macros Chapter 16 The macro editor facilities are arranged under three menus in the editor’s menu bar: 1.02 . Open the Define Panel dialog box.F12) to execute pro-STAR Version 4. The Re-Scan button recreates the list of available macros. Select Assign from the panel’s Macro menu. The Rename button changes the name of a macro file to another name typed in the text box. The Copy button creates new macros by copying an existing macro file to another file whose name must be typed in the text box. Those that were removed from the list will re-appear.02 16-9 . select a panel from the list and display it by double-clicking it. Execute (a) Execute Macro — execute the whole macro (b) Execute Selection — execute only the highlighted lines in the editor window As with panels. The latter can only be deleted outside pro-STAR by using the appropriate operating system command. • • • Note that panel buttons are often used to execute macros.Chapter 16 PRO-STAR CUSTOMISATION Function Keys 3. by setting the button definition to issue command *macro. Click on a free button in the panel. while those created via the New action button but never saved will disappear. the Define Macro dialog box provides additional facilities for manipulating macros. The Delete button allows users to remove macros from the list of available macros but does not delete the corresponding files. This assigns the macro name to the button and generates the appropriate *MACRO command. select Edit from the panel’s Macro menu to open the macro text editor discussed above and type in any further changes Save all changes by selecting Save from the File menus of both macro and panel editors before closing their corresponding dialog boxes Function Keys Users can program the keyboard function keys (F2 . If necessary. as follows: • • The Execute button executes the selected macro.exec This assignment can be made as follows: • • • • • • Open the Define Macro dialog box and highlight a macro in the list. . Available items are: 16-10 Version 4. Command parameters such as ‘VX’ or ‘CX’ may be used and will be interpreted in the normal way. Command strings are limited to 80 characters in length..dialog2. In addition to standard pro-STAR commands..02 . Command string open dialog1. will open the dialog boxes or tools specified. including parameters such as ‘VX’ or ‘CX’. This is done by choosing Utility > Function Keys from the menu bar to display the Edit Function Keys dialog box shown below.PRO-STAR CUSTOMISATION Function Keys Chapter 16 commands or macros. the function keys can also be used to repeat the last executed command and to open dialog boxes. Any valid pro-STAR command (or set of commands if a $ character is used to separate them) can be mapped to individual function keys by typing it in the appropriate text box. Thus: • • Command repeat will literally repeat the last command executed. Chapter 16 PRO-STAR CUSTOMISATION Function Keys Name ANIM BLIS BLLI BLOC CELL CHEC CHEM CLIS COLO CONT COUP CSYS DROP FORE GENE GRAP GRDI GRLO GRRE POST PROP SPLI SPLL STAR TRAN VERT VLIS Description Animation Module Boundary List Block List Block Tool Cell Tool Check Tool Chemical Module Cell List Colour Tool Control Module (unsupported panel) Couple Tool Coordinate Systems panel Droplets panel Convert Foreign Formats panel Convert Generic panel Graph Tool Graph Module Load Graph Registers panel Graph Registers panel Post Register Data List Property Module (unsupported panel) Spline Tool Spline List Convert STAR panel Transient Module Vertex Tool Vertex List The default function key definitions are: F5 – repeat F6 – replot F7 – cplot F8 – zoom.02 16-11 .Defaults (see “Set-up Files” on page 16-1) at the location specified by environment variable STARUSR (or in your current directory.Prostar. This file can be modified either through the Function Keys dialog box within pro-STAR or outside it via any suitable editor.Defaults file in the STARUSR location so that the particular setup that they define is available for any pro-STAR session. Users may find it useful to keep a single .off $replot Note that the F1 key is reserved for displaying context-sensitive.Prostar. on-line Help information on pro-STAR commands (see “Getting On-line Help” on page 2-35) Any changes to the function key definitions are saved in a file called . Version 4. see page 16-1). . A case name may be overridden at any time during a pro-STAR session by choosing File > Case Name from the menu bar. It also determines which files will be used during subsequent file operations.mdl.xxxx. test. pro-STAR creates a set of files whose names are based on a user-supplied model name or case name.02 17-1 . then all its associated files will be called test. These key files are described below: Version 4. Commonly used files A few key files are always read and/or written to by pro-STAR. This displays the Change Case Name dialog shown below: Command: CASENAME Supply a new case name (up to 70 characters long) in the text box provided.Chapter 17 OTHER STAR-CD FEATURES AND CONTROLS Introduction Chapter 17 OTHER STAR-CD FEATURES AND CONTROLS This chapter describes some of the less commonly used features and controls in STAR-CD and covers the following topics: • • • • File organisation. Note that the names of the input and output restart (. naming conventions and general utilisation Special pro-STAR and STAR features and settings The StarWatch utility Hard copy production Introduction File Handling Naming conventions At every session. This changes the default file name but does not affect any files that are already open. if the case in question is called test.ccm) files will be reset by this operation.or four-character filename extension. and will be used for the appropriate input/output operation during the model building and numerical solution processes. Each file name is of the form case. whereas the majority are opened and accessed only in response to a command or a GUI operation. You should always supply a case name at the beginning of a pro-STAR session (see “pro-STAR Initialisation” on page 2-12).ccm. etc. Thus. where xxxx is a three. It is advisable to save data regularly during a session so as to minimise the chance of losing large amounts of information due to user error or system failure. for GUI operations.02 . the model you started out with before making any changes) is also automatically stored as a backup. This displays the Resume From dialog shown below. Alternatively. choose option File > Resume From from the menu bar.bak If you need to save the . Command: SAVE Option File > Resume Model performs the reverse operation. Choosing option File > Save Model from the menu bar instructs pro-STAR to write a full description of your model to this file. Model file (. the file may be selected by clicking the browser button provided and utilising pro-STAR’s built-in file browser facilities (see page 17-9).e. using the specified case name as the file name. i.echo) Used exclusively by pro-STAR and is always opened. Once the editing process is complete. choose option File > Save As from the menu bar. If you need to resume from a .e. The file can be: • • • Reviewed Used for recovery purposes (see “Error messages” on page 2-19) Copied to a temporary file which can be subsequently edited to make changes to the recorded commands (see item 12 on page 17-10). Note that every time you save the model file.mdl file under a name other than the case name. as generated automatically by pro-STAR during the session. in a file of form case. the modified command file can be replayed into pro-STAR using the editor’s file execution facilities (or by typing command IFILE). which allows the name to be typed exactly as required.OTHER STAR-CD FEATURES AND CONTROLS File Handling Chapter 17 Echo file (. its previous version (i. it instructs pro-STAR to read a model description from an existing .mdl file.mdl) Used exclusively by pro-STAR. an existing file may be selected by utilising pro-STAR’s built-in file browser facilities (see page 17-9). shown below. Alternatively. their command equivalents. This displays the Save As dialog. It holds a copy of every command typed by the user or. 17-2 Version 4.mdl file that does not have the same name as the case name. which allows the name to be typed exactly as required. This is especially useful if you want to set up several runs with parametric changes and then submit the job in batch. Once the files have been copied to a suitable directory.drpc) is created. . respectively. To enable you to find out which commands would activate certain features present in your model.vrt. choose File > Save As Coded from the menu bar to display the CDSave dialog shown below: Command: CDSAVE The dialog uses default file names with extensions .inp. cell.Chapter 17 OTHER STAR-CD FEATURES AND CONTROLS File Handling Command: RESUME Problem setup (command) file (. For cases containing droplets.bnd for four files that will contain problem set-up. • • To write model data in text form.evnc. Examples of such instances are: • To allow you to quickly produce a set of coded pro-STAR input files that will re-create the case as defined in the model file.inp) Although the model file is normally saved in binary form. an additional droplet data file (. This will display the Version 4. . and .02 17-3 . the model may be re-activated by choosing File > Read File from the menu bar. For moving mesh cases. event definitions (see “Moving Meshes” on page 12-9) can also be written to file . To facilitate testing of models that were created with a previous version of pro-STAR. vertex and boundary information. Alternative names for any of these files may be entered in the boxes provided.cel. there may be occasions when you need to write the model data in text (coded) form. g. This is done by selecting Modules > Transient from the menu bar to display the Advanced Transients dialog. The file is normally written in binary form but a facility also exists for writing it instead in text (coded) format and to a file with extension . . i.trnc. All data in files .. . If an existing file needs to be used. number and length of time steps. Switch the plot output from the terminal or workstation to the plot file by choosing item Plot > Plot To File from the menu bar (or use command TERMINAL in the form TERMINAL. as normal.02 . The file may be written in either binary or text (coded) format. for moving mesh cases.cel.evnc will be read in automatically. machine-independent representations of a set of plots.trns) This is used exclusively by pro-STAR for transient problems specified by means of load steps (see “Load-step based solution mode” on page 5-6) and contains all additional information (changes to boundary conditions.drpc (if present) and.OTHER STAR-CD FEATURES AND CONTROLS File Handling Chapter 17 Input Coded File dialog shown below: Command: IFILE Check that the file shown in the File Name window is correct and then click Apply.bnd. Alternatively.g. or by typing command TRFILE. CD-adapco supply source code for several decoding programs that drive hard-copy devices in a variety of formats (e. Graphical output is now Version 4. pro-STAR’s built-in file browser can help locate it.plot) This is used exclusively by pro-STAR and is always open to receive neutral plot information. To make use of the neutral plot facility: • • Specify the plot file name (if other than case. Transient history file (.) needed for such problems. X-window workstations). Postscript). This is done via the Advanced Transients dialog (see “Load step controls” on page 5-10).plot) and type (if not CODED) using command NFILE. or screen output devices (e. etc. . These programs can also serve as templates for constructing plot drivers for other.e.vrt. Plot file (. use command CDTRANS. You must make this file available to your current session before changing or adding data concerning the analysis.FILE • 17-4 Perform the plotting operations required. unsupported devices. specifying the file name in the box provided at the bottom of the dialog and then clicking Apply. . or assigned to different boundary regions (c) the cell type definitions are changed The file is created by selecting File > Write Geometry File from the menu bar to display the Geometry File Write dialog shown below: Command: GEOMWRITE The input required is: (a) File Name — enter a name in the text box provided or click the adjacent button to select an existing file using pro-STAR’s built-in file browser (see page 17-9) (b) File Type — select the file format according to the solver (CCM.02 17-5 .ccm.e. i. pro-STAR saves all cell topology and model geometry information in the file once mesh building is complete. choose option Plot To Screen from the Plot menu.ccm) This file has a special format that facilitates different sets of information to be stored in it. Details of data representation in the neutral plot file can be found in the Post-Processing User Guide.Chapter 17 OTHER STAR-CD FEATURES AND CONTROLS File Handling • diverted to the file instead of being displayed on the screen. subtracted. Cells are defined as a collection of faces. The file must be rewritten whenever (a) the mesh geometry is modified (b) boundaries are added.bak Version 4. It is written and read by both pro-STAR and STAR in the following ways: 1. To restore normal operation. BAE) for which the geometry file is intended (c) Geometry Scale Factor — an optional scale factor applied to all dimensions of the problem’s geometry (d) Write Backup File — define the action to be taken if the specified repository filename already exists in your current directory: i) Backup — the existing file is renamed as casename. CEDRE. Appendix B. a general polyhedral cell definition is used regardless of the actual cell shape. Data repository file (. ccm.. (b) For restart runs. The table below lists the names of the states and the data stored in them. The file is created by selecting File > Write Problem File from the menu bar to display the dialog shown below. It is written independently of the geometry file and should be rewritten every time any of the above model parameters is modified. It also contains all material property values. STAR reads the geometry information contained in the file and then appends the solution results at the end of the analysis. STAR reads in addition the results of a previous (partially converged.2.bak1 already exists.bak2 if casename..). STAR’s action is one of the following: (a) For initial runs. Apart from storing problem geometry data.ccm. pro-STAR will also (a) read the file for post-processing purposes.geom (decomposed) .02 . solution control settings. to make contour.3. The available states in a given file may be displayed using command CCLIST. STAR also stores them in this file. Type of data Problem geometry for sequential runs Problem geometry for parallel runs Solution (Restart) data Mapped Solution (Restart) data Field residuals STAR-CD 3.bak already exists. The new analysis results then overwrite the previous ones at the end of the run.ccm. 3. vector or graph plots of any variable calculated by STAR.e.geom .pst .ccm. State name default geom_par Restart_1 smap Residue_n n=1. It contains information on what kind of analysis is to be performed and what data are to be printed or saved for post processing. “Solution Control with Mesh Changes” in this volume) Each set of data stored in the repository file is called a “state”. Note that a filename other than the default 17-6 Version 4. ii) No Backup — the geometry information is overwritten 2. or casename.smap . (b) write mapped solution data when an existing mesh is refined (see Chapter 5.prob) This is written by pro-STAR and read by STAR. interrupted or transient) analysis before starting the new solution. boundary conditions and initial conditions. (c) If solution residual values are required as part of the analysis.2X equivalent file .bak1 if casename..OTHER STAR-CD FEATURES AND CONTROLS File Handling Chapter 17 (or casename. i. etc.rpo Problem data file (. however.02 17-7 .ccm) file.Chapter 17 OTHER STAR-CD FEATURES AND CONTROLS File Handling (casename. Version 4. Appendix B in this document contains a complete list of all files that can be written or read by either pro-STAR or STAR. It is used by a subsequent pro-STAR post-processing run to make contour or vector plots based on the selected data.prob) may be entered if necessary in the text box provided.pstt) This is written by STAR and contains selected transient analysis data at pre-defined points in time (see “Output controls” on page 5-12). only the files shown below are ever needed. and then highlighting item FILE). so it cannot be used for restarting the analysis. that function can be performed only by using the data repository (. File relationships The use and relationship between files in the STAR-CD environment is illustrated by Figure 17-1. The same information may also be displayed on-line in the Help dialog (choose Help > pro-STAR Help from the menu bar. For the great majority of problems. Note that the file holds only part of the available information on the model. Command: PROBLEMWRITE Transient post data file (. select Misc. from the Module pop-up menu. prob Boundary conds. This is useful. for example. This activates the Post Convert dialog shown below: Commands: You may then • SMCONVERT PTCONVERT • 17-8 select option Solution Monitoring or Particle/Droplet Track depending on the file type you wish to convert. in manipulating and displaying the data outside the pro-STAR environment or for checking the validity of the file contents.echo Command echo case. pro-STAR provides a utility for converting solution monitoring and droplet track data files to coded (text) format and vice versa. the second with droplet track data conversion (see “Trajectory displays” on page 9-8) or particle track data conversion (see “The Particle Track File” on page 7-6 of the Post-Processing User Guide) enter the name of the file containing the data to be converted (Input File with Version 4.mdl Model data case.plot Neutral plot pro-STAR case.pstt Transient output data Figure 17-1 STAR-CD file use In addition to solution and transient post data files. The utility allows conversions between a variety of formats and is accessed by selecting Tools > Convert > Post from the menu bar.ccm Solution data case. The first option deals with residual or solution monitoring data conversion (see Chapter 5. “Output controls”).ccm Geometry STAR case. Solution params. case.OTHER STAR-CD FEATURES AND CONTROLS File Handling Chapter 17 case.02 .trns Transient history data case. The button displays the File Selection dialog shown below: The scroll lists and filters included in the above dialog allow easy navigation through various levels of sub-directories until the required file is located.rsic or . i. the largest amount is needed while the geometry (. use pro-STAR’s file browser facility.ccm) file is being written. While some scratch space is used for hidden-line plotting. Finding files — If you are not sure of the exact location or name of an existing file. Version 4. using the same dialog but with Input now being Coded and Output being Binary.e. These are opened automatically and deleted at the end of the session.02 17-9 .trk) or select it using pro-STAR’s built-in file browser (see page 17-9) choose the file type (normally Binary) from the available options in the adjacent pop-up menu enter the name of the file that will store the converted data (Output File with extension . File manipulation The file-manipulation related capabilities of pro-STAR are as follows: 1.Chapter 17 OTHER STAR-CD FEATURES AND CONTROLS File Handling • • • extension . In the course of a session pro-STAR also opens several scratch files. plus a reversal of the file name extensions.trkc) choose the file type (normally Coded) from the available options in the adjacent pop-up menu The above operation may also be performed in reverse. converting the text file back to binary format. Their use is normally transparent except when their size exceeds the amount of free space on your disk. This is activated by clicking the browser button included in numerous GUI dialogs. The space used varies linearly with the number of vertices present and the maximum number of cells connected to any single vertex.rsi or . 5.02 .mdl)” above) by choosing File > Resume From. 17-10 Version 4. Saving the current model description in binary format to file . as described above. 11. 9. Writing the geometry file (see “Data repository file (. 3. As noted in the section on “Commonly used files” on page 17-1. the new input stream can itself contain IFILE commands that will direct input to yet another source file and so on. 10. for example. 4. Restoring a previously created model from a saved model file (see “Model file (. Saving the model description in text (coded) format.) every time a session starts.OTHER STAR-CD FEATURES AND CONTROLS File Handling Chapter 17 2. as described above. When used for the first time in a pro-STAR session. input switches back to the terminal automatically at the end of the specified file. and vice versa. an echo file should be copied and renamed before using it as a command file. 6. etc. by choosing File > Save As Coded from the menu bar.out). RESUME will also automatically read and execute commands stored in a special file called PROINIT (see “Set-up Files” on page 16-1).inp) containing pro-STAR commands. for use in other programs or for later review. In the latter case. (b) User subroutine files — these contain special user-supplied FORTRAN code and are discussed in detail in Chapter 14. To avoid problems. 8. The command also supports a ‘nesting’ capability.e. i. plot type. Printing a summary of all currently open files by typing command FSTAT. Switching output from a terminal screen (or standard output) to a disk file (of form case. This can be done at any time during a session using command OFILE. 12. viewing angle.. Writing the problem data file (see “Problem data file (.ccm)” above) by choosing File > Write Geometry File from the menu bar. The facility enables you to save lists of various pro-STAR items.mdl. Closing a previously used file by typing command CLOSE. Files that may be conveniently manipulated using this editor are: (a) Command files — these allow execution of a set of pre-recorded pro-STAR commands. The command may also close all currently open files. and vice versa. by choosing File > Save Model from the menu bar. from the menu bar. File editing via pro-STAR’s built-in editor — This is activated by choosing File > Edit File from the menu bar to display the panel shown below. a common source for them are echo files from previous pro-STAR sessions. Switching program input from a terminal (or standard input) to any disk file (of form case. Repositioning a previously used file (including a pro-STAR macro file) to its starting point by typing command REWIND. however. using either the pro-STAR editor’s Execute menu options (see item 12 below) or by typing command IFILE. This can be done at any time during a session.. 7. Using parameter NONE with this command turns the output off completely.prob)” above) by choosing File > Write Problem File from the menu bar. This provides a very convenient way of setting up pro-STAR in a standard way (regarding. (d) Clear All — clear the editor window. Find Again — repeatedly find the selected characters. as follows: File (a) Open — open a specified file. (c) Save As — save the current changes to a different file. The dialog box above re-appears to aid specification of the destination file location. (e) Quit — terminate the editing session. Replace — find a character string and replace it with another string. Find Selection — find the selected characters in the file body.02 17-11 . This activates the File Selection dialog shown on page 17-9. Edit (a) Find — find a character string. Both strings are typed in the dialog box shown below.Chapter 17 OTHER STAR-CD FEATURES AND CONTROLS File Handling The available facilities are arranged under three menus in the editor’s own menu bar. typed in the dialog box shown below. (b) (c) (d) (e) Mark Selection — mark the selected characters for subsequent searches. enabling the required file to be located. Version 4. (b) Save — save the current changes. You should ensure that these values are correctly set before using STAR-CD. see the description of command TSCALE in the Commands volume) STARFONT3 / starfont3 Font name and size to use for entity numbers (NUMBER command).02 . STARFONT0 / starfont0 Font name and size to use for plot title. (b) Execute Selection — execute only the highlighted lines in the editor window. respectively (see “Panel definition files” on page 16-5) STARBROWSER (not needed for Windows ports) Path to the user’s choice of Internet browser (Netscape or IE) that will be launched from the pro-STAR Help menu (see page 2-37).or mouse-driven cut. The current list of such variables is as follows: MACRO_LOCAL and MACRO_GLOBAL Paths to the local and global pro-STAR macro directories. The user’s search path must be amended to include the directory defined by this variable. The default is to run Mozilla from your current working directory. respectively (see “Macros” on page 16-6) PANEL_LOCAL and PANEL_GLOBAL Paths to the local and global pro-STAR panel directories. the usual keyboard.OTHER STAR-CD FEATURES AND CONTROLS Special pro-STAR Features Chapter 17 Execute (Command files only) (a) Execute All — execute all commands in the file. copy and paste functionality is also available with the editor window. In addition. The syntax for setting environment variables depends on the shell program you are using (if in doubt type the command echo $SHELL). graph title and main axes label (see the description of command TSCALE in the Commands volume) STARFONT1 / starfont1 Font name and size to use for the contour and vector scales (see the description of command TSCALE in the Commands volume) STARFONT2 / starfont2 Font name and size to use for the secondary contour and vector scales (for droplets and particle ribbons. Special pro-STAR Features pro-STAR environment variables pro-STAR uses the values of several environment variables. plot legend. This is equivalent to typing command IFILE in pro-STAR’s Input window. x and y tick labels on graphs and local coordinate system axes (see the description of command 17-12 Version 4. Some specify the path to various system directories while others control the operation of the system. The most usual variation from the default values is in the maximum number of cells (MAXCEL) and vertices (MAXVRT). In any of the above situations. You may also exit here without modifying or creating any files. Otherwise. file param. pro-STAR will automatically write a new local param. containing a user-supplied Tcl/Tk script (see “The Users Tool” on page 2-35) STARUSR Path to pro-STAR files PRODEFS (abbreviations). STAR_TCL_SCRIPT Path to the location of file STARTkGUI.tcl. Version 4. prosize asks: Is your mesh primarily hex or tet? (Answer H or T) (The T option should be chosen for wholly or predominantly tetrahedral meshes.Prostar.prp. while entering -1 will terminate the script and use the remaining defaults to write param. “Running a STAR-CD Analysis”. if you are having problems with available memory in your machine).mdl) file being read. etc.Defaults (see “Set-up Files” on page 16-1) Resizing pro-STAR pro-STAR is a dynamic-memory executable code and requires a file called param. It is almost always necessary to resize the pro-STAR executable to cater for special problems (such as moving mesh problems) or to accommodate cases with a larger number of cells.Chapter 17 OTHER STAR-CD FEATURES AND CONTROLS Special pro-STAR Features TSCALE in the Commands volume) Note: Variables STARFONT 0-3 described above apply only to X-window plotting. The file contains a list of parameters that determine the data size of the executable on start-up. A carriage return instructs the script to use the indicated default value.prp to be present in your current working directory. (or a smaller number. the script prompts you to specify the values of the parameters to be stored in param.prp.02 17-13 . This is accessed by typing prosize The script first asks whether you want to modify some of the parameters in the current file or create a brand new param. If continuing. This happens the first time pro-STAR is run using the prostar script described in Chapter 2. They have no effect on OpenGL based plotting as the fonts system there is entirely different.prp. incomplete. the default values suggested by prosize should be sufficient for most cases. Rather. vertices. PROINIT (initial set up) and . By running the prosize script. a new version of the file containing parameters of the right magnitude must be created in one of the following ways: 1.prp based on the values in the model (. H is appropriate for all others.prp. including meshes containing trimmed cells) After this. and also on any values that could be read from an existing param. If this file is missing.prp should be modified but this should never be done using a text editor. or out-of-date. However. vertices.prp file as param. the required special pro-STAR executable may be created using script prolinkl. 17-14 Version 4.bak and write the new parameters into a new param. You select the location of temporary files by setting an environment variable.OTHER STAR-CD FEATURES AND CONTROLS Special pro-STAR Features Chapter 17 2. Either way.f in the current directory. and is not supported in Windows ports at present. after which you may continue as normal. to the path name of the directory where pro-STAR should write the temporary files. In practice. the parameter values are changed internally without changing the param. Use of temporary files by pro-STAR Choosing the location of temporary files You can control the location of most pro-STAR temporary files for POSIXcompliant computers. it is possible to clear all model parameters (i. this means on a fast hard disk on the same computer as that doing the calculations (rather than on a remote disk accessed through a local area network).e. If during the session it is found that the value of any sizing parameter(s) is insufficient.so or . In such a case.o) and converted into a dynamically-loaded shared object (. delete all cells.f. That file will be compiled into object code (user1. boundaries. after running pro-STAR with a given model. pro-STAR will sometimes be able to adjust the parameter value(s) automatically and then continue. This option refers to subroutines that work in conjunction with pro-STAR. named TMPDIR. The directory with the shared object must be added to the shared object library path (usually LD_LIBRARY_PATH) in order to be found and used by any subsequent pro-STAR runs. To use the new values in future pro-STAR sessions. prolinkl will advise the user on how to create this path for the given operating system.prp file. This is accessed by typing prolinkl The script looks for a file named user1. you will need to save them explicitly via a MEMORY.WRITE instruction.prp file.) but leave the current memory size intact. a directory called /tmp. option MEMORY of this command will also reset the pro-STAR executable back to the size given in the param. This is done using command WIPEOUT and is useful if you want to abandon the current model and start a new one from scratch without exiting from pro-STAR. a warning message will appear in the I/O window. you may need to use a user-defined subroutine file.prp file. Note that. This command can be used only to increase the parameter sizes. user1. Special pro-STAR executables On occasion. By issuing command MEMORY from within the pro-STAR session. Note that the usual location for Unix temporary files.sl or . This will rename the existing param. not STAR. You should ensure temporary files reside where there is sufficient capacity and where they can be accessed quickly. etc.dll depending on the operating system). Furthermore. in most cases you will be prompted to enter an appropriate new value for the indicated parameter(s) using MEMORY. often has insufficient capacity for pro-STAR’s temporary files.02 . 02 17-15 . then no further setup is required. If they are not. including your own You may select the variables whose solution progress you wish to monitor You may adjust the display characteristics (e. you might have to manually delete abandoned temporary files after a crash or halt. For other systems. the StarWatch daemon (a communication program) and StarWatch. perhaps because they Version 4. The StarWatch Utility This is a free-standing utility that enables you to monitor the progress of a selected STAR job running anywhere in your computer network. it will crash if you do. Specific advantages of StarWatch are: • • • • You can monitor progress of a number of separate STAR jobs The jobs may be running on any machine in your network. pro-STAR may leave temporary files behind if it crashes or you halt its execution. StarWatch uses ports 6200 to 6206 to establish communication between the STAR executable. as shown below. For POSIX-compliant systems. scaling) of the monitored variables Running StarWatch By default.g. the operating system automatically deletes most temporary files if pro-STAR halts or crashes. the display program that runs on your screen. The monitoring is done from a special window opened by StarWatch. If ports 6200 — 6206 are acceptable.Chapter 17 OTHER STAR-CD FEATURES AND CONTROLS The StarWatch Utility Deleting temporary files Take care not to delete pro-STAR’s temporary files during a calculation. or if you want to monitor the progress of another currently active job. then send this application to the background also. then an administrator must edit the /etc/services file and add the following lines: star-chartd star-chart1 star-chart2 star-chart3 star-chart4 star-chart5 star-chart6 6200/tcp 6201/tcp 6202/tcp 6203/tcp 6204/tcp 6205/tcp 6206/tcp # # # # # # # Star/Stripchart client/server daemon Local Stripchart 1 Local Stripchart 2 Local Stripchart 3 Local Stripchart 4 Local Stripchart 5 Local Stripchart 6 where port numbers 6200 — 6206 can be replaced by any set of port numbers. Note that: • • • Only STAR jobs owned by you and only those that have registered with the StarWatch daemon can be selected Registration usually takes place roughly at the end of the first iteration If STAR cannot find the daemon. The StarWatch application panel should appear on your screen. If the defaults are not acceptable. Start your STAR job in the same window using the -watch option. Choose the name of the machine running your job in the Select Host dialog shown below and click OK. “Running a STAR-CD Analysis”. Note that you may also start STAR first and then StarWatch. StarWatch will start automatically as soon as STAR itself begins execution and will open a monitoring window like the one shown above (see Chapter 2. The only proviso is that if the ports are changed on one system. Step 2 Go to the StarWatch panel and select option Host from the Connect menu. Version 4. Step 6).02 17-16 . Note that when running a parallel job. If you are not using STAR GUIde. you may open the StarWatch window explicitly by following the steps below: • • • Open a new window on your computer or go to an existing one Type starwatch.OTHER STAR-CD FEATURES AND CONTROLS The StarWatch Utility Chapter 17 conflict with other programs using those ports. they can be set to any ports that the user (or more likely) system administrator wants to use. it will keep trying for a small amount of time and then continue without trying further contact. Step 1 If using the STAR GUIde environment to run a numerical analysis interactively. the same change must be made for all systems for which StarWatch communication is required. the -watch option must precede any other options used. Monitored variable Choose the flow variables to be monitored. in terms of either field or residual values. 2.02 17-17 . The method of selecting scalars is the same as for the main (global) variables. Material (stream) number In multi-stream applications. Many of the parameters set in pro-STAR can be viewed and altered dynamically while the solution is in progress by selecting Settings > STAR Control Variables from the StarWatch menu bar. This brings up the Star Control Variables dialog shown below: Version 4. Note that since only seven quantities can be monitored. 3. The button label changes from Plot Field Values to Plot Residual Values and vice versa. The labelling and scale of the adjacent graph also changes accordingly. by selecting View > Selected Data > Scalar Variables from the menu bar. The latter appear in the Legend section under the Property column and comprise the three velocity components.Chapter 17 OTHER STAR-CD FEATURES AND CONTROLS The StarWatch Utility Now choose the PID of the STAR job you wish to monitor from the list displayed in the Select STAR Job dialog and click OK. depending on your choice. if present in your model. select the stream you wish to monitor using the Material Number slider control. It is also possible to monitor changes in scalar variables. option View > Select Scalars lets you decide which scalars you want to look at. Choosing the monitored values The following choices are available: 1. Controlling STAR At the beginning of a numerical analysis. The contents of the Legend section and the graph labelling will change accordingly. by opening a secondary (Select Scalars) dialog in which the required scalars and the order in which they appear in the StarWatch display may be determined. The colour used to display each variable is shown next to the name. Field or residual values Select the type of variable to be displayed by clicking the toggle button at the bottom of the Legend section. StarWatch should now start displaying the monitored flow variables against iteration number or time step. by clicking the option buttons next to the variable names. STAR reads all files prepared for it by pro-STAR. turbulence kinetic energy and dissipation rate. pressure and temperature. 02 . Control information will be written to file .info NDUMP Frequency of writing data to file .ccm 17-18 Version 4.OTHER STAR-CD FEATURES AND CONTROLS The StarWatch Utility Chapter 17 The dialog’s purpose is to allow the user to interactively change the values of several STAR solution and output control parameters. as shown above.T.ccm NFSAVE Backup frequency (frequency of saving file . Boundary data will be written to file .T.info IRESI =.T.pst_iternum) NCRPR Number of cell Courant numbers (starting from the largest) to be printed out NFRRE Iteration frequency for dumping residuals to file .info BOECHO =.info ITEST =. Write all solver convergence information to file . Write all conservation balance information to file . These are grouped into six tabs according to function. The meaning of the available parameters is listed in the table below: Parameter Meaning General Settings DT Time step size MAXCOR Maximum number of correctors for the PISO algorithm RESOC Residual tolerance for the PISO algorithm SORMAX Overall convergence criterion IJKMON Monitoring cell number for fluid domains File Output ECHO =. and all act in the same way.T. by looking at the displayed values at the end of each Version 4.Chapter 17 OTHER STAR-CD FEATURES AND CONTROLS The StarWatch Utility Parameter Meaning Under-Relaxation Factors FPCR Under-relaxation factor for pressure correction (PISO) FUVW Under-relaxation factors for velocities FP Under-relaxation factor for pressure FTE Under-relaxation factors for k and ε FT Under-relaxation factor for temperature FTVS Under-relaxation factor for turbulent viscosity FDEN Under-relaxation factor for density FLVS Under-relaxation factor for laminar viscosity FCON Under-relaxation factor for heat conductivity FR Under-relaxation factor for radiation Blending Factors GGUVW Blending factor for velocities GGKE Blending factor for k and ε GGT Blending factor for temperature GGDEN Blending factor for density GGSCA Blending factor for scalars Residual Tolerances SORU Solver residual for U velocity SORV Solver residual for V velocity SORW Solver residual for W velocity SORP Solver residual for pressure SORK Solver residual for k SORE Solver residual for ε SORT Solver residual for temperature Number of Sweeps NSWPU Total number of solver sweeps for U in one run NSWPV Total number of solver sweeps for V in one run NSWPW Total number of solver sweeps for W in one run NSWPP Total number of solver sweeps for P in one run NSWPK Total number of solver sweeps for k in one run NSWPE Total number of solver sweeps for ε in one run NSWPT Total number of solver sweeps for T in one run Solution control can then be exercised as follows: 1. During execution.02 17-19 . monitor the behaviour of normalised residual sums for each variable being solved for. hist before re-running a job. STAR will make the same changes to the job that you made during the original run (so you can duplicate and repeat your changes to. e. in two ways: • As numerical values in the Iteration / Time Step Data section. the parameter(s) will change inside STAR from the beginning of the next iteration (or time step) following the Send operation and a marker will be placed on the graph indicating the point at which something was changed. The maximum and minimum values reached so far and the change since the previous iteration are also shown. as specified in the “Monitoring and Reference Data” STAR GUIde panel. or click Send to confirm it. You can now either Cancel the change and then make others. • • Manipulating the StarWatch display The monitored variables chosen in the previous section are continuously displayed in the StarWatch panel as the calculation progresses. In the latter case.g. 3. If you do not copy a line in.ctrl. delete casename. If you do not want the run changed the same way. under-relaxation factors). If you want to change one or more of them.ctrl. look at the flow variable values at the monitoring location. by (a) re-specifying an under-relaxation factor in order to speed up solution convergence (b) increasing the value of parameter SORMAX to stop the run at an earlier stage The values currently in use are shown on the dialog.02 . In addition. you may decide to alter the course of the calculations by altering a model parameter. If you re-run a job without removing the control history file. As a graph of variable value versus iteration number/time step. • The detailed appearance of this graph may be adjusted as follows: 17-20 Version 4. StarWatch also keeps a control history file called casename. You do not have to have StarWatch running for the above changes to take place at various iterations.hist recording the changes made during a run. enter the new value in the appropriate box(es) and click Apply. Note also the following points: • • The colour of marker matches the colour of the tab in which the alteration was made and STAR itself will print a message indicating the change If you make multiple changes.OTHER STAR-CD FEATURES AND CONTROLS The StarWatch Utility Chapter 17 iteration or time step. STAR will read the casename.ctrl file and make the changes to the run at the appropriate iteration. you can highlight any one line and use the dialog’s Edit menu to copy/paste that line into other boxes and then edit any of the numbers. This change is treated as pending. While monitoring this display. say. 2. the code assumes that you are making changes to the last line. which now only shows the graph and associated legend. Note that the number of panels that may be open simultaneously will depend on the setting specified in file /etc/services. Display size Select View > Partial View from the menu bar to reduce the extent of the StarWatch display. depending on the variable being monitored.FILE. 5. Step 2 Select Connect > Host.. after the job has finished executing.plot)” on page 17-4).Chapter 17 OTHER STAR-CD FEATURES AND CONTROLS Hard Copy Production 1. as described in “Running StarWatch”. you may simply open another window and load another StarWatch panel. type TERMINAL. Alternatively. Selecting View > Full View restores the original display. Once the required plot is on-screen.e. Vertical range Use the vertical slider to move the graph window to the desired variable value range. Whether you need to do this or not depends on the vertical scale chosen. follow the procedure below: Step 1 Select Connect > Disconnect from the menu bar to terminate monitoring of the current job. StarWatch should now start displaying the monitored variables for the new job. Horizontal scale Use the H: slider to achieve a reasonable scale. Note that this scale changes automatically as you switch from residual to field values. Hard Copy Production Neutral plot file production and use To obtain hard copy of a screen plot. mode) Version 4. Vertical scale Use the V: slider to achieve a reasonable scale. Step 3 Choose the job’s PID from the list displayed in the Select STAR Job dialog and click OK. Monitoring another job If you have several STAR jobs running simultaneously and you want to switch your monitoring to a different job.02 17-21 . 4. depending on the number of iterations 2. switch the graphical output temporarily to the neutral plot file (see “Plot file (. colour-fill.RAST (switches to the neutral plot file in raster. i. 3. Horizontal range Use the Iteration Number / Time Step slider to move the graph window to the required iteration range. enter the name of the machine running the job you wish to monitor in the Select Host dialog and click OK. The latter are special graphics post-processors that either • • generate files suitable for plotting on a given type of hard-copy device. or display the contents of the neutral plot file on your screen (see Appendix B in the Post-Processing User Guide for more details). The PLOT programs available on your particular installation are normally accessed by opening a window and typing plot This produces a response of the form: Please enter the required plot driver: Available drivers are: ai fr gif hp ps pst su x xm [xm] where ai — Adobe Illustrator file output fr — Adobe Freehand file output gif — GIF file output hp — HP Graphics Language file output ps — PostScript file output pst — utility for adding an extra title to an existing PostScript file su — utility for reducing the size of an existing neutral plot file by removing hidden polygons x — X-windows terminal display xm — X Motif graphics display 17-22 Version 4. i.plot.Gray option in the Color Tool or by typing command CLRTABLE. This can be done either by selecting the Post . line-contour mode) followed by REPLOT (sends the picture to this file) TERMINAL. It is recommended that colour plots destined for a black-and-white printer should be converted to the grey-scale shading scheme (see “Colour settings” on page 4-10) before sending them to the neutral plot file. process the pictures stored in the neutral plot file outside the pro-STAR environment using one of the supplied programs in the PLOT suite.GRAY To produce the hard copy.OTHER STAR-CD FEATURES AND CONTROLS Hard Copy Production Chapter 17 or TERMINAL. (switch output back to the screen) The above process can be repeated as often as is necessary to write all required plot data to file case.VECT (switches to the neutral plot file in vector.e..02 .FILE.. Scene file production and use STAR-CD scene files provide a convenient way to store a fully post-processed model in a format that can be subsequently viewed with the lightweight and quick STAR-View viewer program. To produce high-resolution hard copies in extended mode. A STAR-CD scene file (extension . Once this file is written. unlike conventional hard copies produced using pro-STAR’s neutral plot facilities. STAR-CD scene files store a full 3-D representation of the current model so the view can be rotated. layers. Select or type the desired scene file name into the File Selection dialog box which appears and press OK to write the file. pro-STAR command SCENE can be used to record the file. including the current plot and any labels. However. and other screen information. Alternatively. and smooth-shaded contour plots cannot be represented in the neutral plot format. select Utility > Write STAR-CD Scene File from the main pro-STAR menu. where filename. and zoomed interactively in the STAR-View program.02 17-23 . translucency. and smooth-shaded contours. To produce such a file. legends.scn is the file name containing the desired scene. Version 4. simply run the STAR-View program by typing starview filename.Chapter 17 OTHER STAR-CD FEATURES AND CONTROLS Hard Copy Production Type the desired option and then follow the instructions on your screen. use the high-resolution screen capture technique described in Chapter 2.scn in an X-window.scn) stores the current state of the extended-mode graphics window. supplying additional information as required. the view in the model can be manipulated via the mouse in exactly the same way as in pro-STAR. Once the latter is loaded. “Plotting Functions”). Once the desired plot is achieved. “Screen capture”. translated. including multiple layers. Note also that extended mode features such as translucency. This can include any effects available in extended mode. first generate the desired plot in extended (OpenGL) mode (see Chapter 2. Note that options such as xm are suitable for screen displays while options such as ps are for hard copy production. . APPENDICES CCM USER GUIDE STAR-CD VERSION 4.02 CONFIDENTIAL — FOR AUTHORISED USERS ONLY © 2006 CD-adapco . . Command names may be abbreviated by the first four letters (with one exception: *ENDIF). The keyword ‘ALL’ may be used in lieu of any vertex. range to denote that all items are to be used for the range. the new line will begin a new argument. titles and screen labels are case-sensitive) 3. In NOVICE mode (see command EXPERT). All terms are evaluated strictly from left to right. Any command may be entered from any module 9. however. Each operator must be separated by blanks or a comma from the numbers or parameters on either side. 6.. Command ABORT may be used at this prompt to abort the current command without performing any action. the total number of characters in a command line formed in this manner may still not exceed 320 characters. Any command string with an exclamation mark (!) in column 1 is interpreted as a comment (and therefore not executed). cell. etc. Input is mostly case-insensitive.1) Version 4. 8.ALL and CTMOD..FLUID) 12.Appendix A pro-STAR CONVENTIONS Command Input Conventions Appendix A pro-STAR CONVENTIONS Command Input Conventions 1. (Examples: CPDEL. A single command line may not be longer than 320 characters 2.02 A-1 . Individual arguments are not continued on a new line. *SET or *GET commands. Basic arithmetic is allowed on all command lines. boundary. 7. A + 7 1000 / B is interpreted as VLIST 100 to (A+7) by (1000/B). Double plus signs (++) at the end of a line indicates that the next line is a continuation of the current line.. Fields in a command string must be separated by a comma or by any number of spaces. where A and B are numeric parameters defined by the *ASK. 11.ALL. 10. Any number of lines may be continued in this manner to form a single command line. (Examples: CLIST. both capital and small letters are accepted (arguments such as file names. For example. The appropriate item set keyword may be used in lieu of most item ranges to denote that all items in the set are to be used for the range. the program will prompt for arguments needed to execute the command. 5. Argument keywords may also be abbreviated by the first four letters (with one exception: parameter arguments for the MEMORY command) 4. Multiple commands may be stacked on a single line.. the following command VLIST 10 * 10.CPSET and VLIS. separated by a dollar sign ($).VSET. Keyword VCRS CCRS BCRS SCRS BLKCRS DCRS Select Vertex set Cell set Boundary set Spline set Block set Droplet set 14.0.CCRS). (Example: CLIST.pro-STAR CONVENTIONS Command Input Conventions Appendix A Keyword VSET CSET BSET SPLSET BLKSET CPSET DSET Item Set Current vertex set Current cell set Current boundary set Current spline set Current block set Current couple set Current droplet set 13.1.02 . The following keywords may be used in lieu of entity numbers.3. Certain keywords (which may also be used in lieu of entity numbers) will cause pro-STAR to display the crosshair cursor in the plot window and expect A-2 Version 4.0) Keyword MXV MXC MXB MXS MXK ICUR Interpreted As Highest numbered vertex + 1 Highest numbered cell + 1 Highest numbered boundary + 1 Highest numbered spline + 1 Highest numbered block + 1 Currently active coordinate system 15. (Example: V.2.0.MXV. The following keywords may be used in lieu of many item ranges to display the crosshair cursor in the plot window so the user may select a set to be used as the range. Numbers in parentheses represent defaults for the immediately preceding variable. Words between slashes (e. as specified by the following description: (Example: STLIST.02 A-3 . Variables beginning with ‘NV’ refer to vertices Variables beginning with ‘NC’ refer to cells Variables beginning with ‘NB’ refer to boundaries Variables beginning with ‘NSPL’ refer to splines Variables beginning with ‘NBLK’ refer to blocks Variables beginning with ‘NCP’ refer to couples Variables beginning with ‘NDR’ refer to droplets Version 4. 2. 3. /ANY/ALL/) represent legal alternatives for the field.SXT) Keyword BLKX BX BXP BXR CX CXC CXG CXM CXP CXS CXT DRX DRXT SX SXC SXG SXT VX Select Block Boundary Boundary Boundary Cell Cell Cell Cell Cell Cell Cell Droplet Droplet Spline Spline Spline Spline Vertex Interpreted As Block number Boundary number Boundary patch number Boundary region number Cell number Cell colour index Cell group number Cell material number Cell porous number Cell spin index Cell type number Droplet number Droplet type number Spline number Spline colour index Spline group number Spline type number Vertex number Help Text / Prompt Conventions 1.g.Appendix A pro-STAR CONVENTIONS Help Text / Prompt Conventions the user to select an item. the extension default will be overridden and the exact name within the quotes will be used. If you enclose the file name in quotes.pro-STAR CONVENTIONS Control and Function Key Conventions Appendix A Control and Function Key Conventions 1.OFF $REPLOT File Name Conventions The default name for any file read or written by the program is casename.OFF $REPLOT Query for help ZOOM.02 . The default function key short-cuts are: Function Key F5 F6 F7 F8 Default Command Repeat last command REPLOT CPLOT ZOOM.OFF $REPLOT QUIT REPLOT SAVE.ext.. where casename is defined by the user and ext is the file name extension. A-4 Version 4. Function key short-cuts can be defined or changed using the Function Keys option in the Utility menu. Zoom out (by a factor of 2) Zoom in (by a factor of 2) 2.ALL ZOOM. The following short-cuts using the Ctrl key are available: Control Key Ctrl-a Ctrl-e Ctrl-h Ctrl-o Ctrl-q Ctrl-r Ctrl-s Ctrl-w Ctrl-z Command CSET. cgns .bnd .cgrd .cpfz .fac Version 4.erd2 .drpc . previous version) of the current pro-STAR model file (binary) Default input/output for boundary definitions STAr file used for storing beam tracking data STAR file used for storing coal combustion data STAR-CD data repository (restart) file (binary/direct access) Default input/output for cell definitions Default output for surface cell definitions Default input/output for CGNS data files Default input file containing grid change commands Default output file for chemical scheme definitions (coded) Default temporary storage of ‘frozen’ vertex data used with the SAVE and MAP options of command CPFREEZE Default input/output for coupled cell definitions Editable file for interactive solution control Tecplot™ post data output file Post data file created when the solution diverges ICEM CFD™ post data output file Default output for droplet definitions (written with command PROBLEMWRITE) Default input/output for droplet data (coded) File for storing engineering data for cell monitoring File for storing dispersed-phase engineering data for cell monitoring Echo of all input typed by the user Default input/output for ANSYS™ element definitions File for storing engineering data for boundary region monitoring File for storing dispersed-phase engineering data for boundary region monitoring Default transient event save file (binary/direct access) Default input/output for ASCII event data files File containing cell face definitions B-1 .elem .div .btr .02 Usage Default input/output for recording animation commands Default save file for animation options Backup (i.ecd .cel .dat .ctrl .e.ani .ecd2 .cpl .cel .anim .evnc .erd .Appendix B FILE TYPES AND THEIR USAGE Appendix B FILE TYPES AND THEIR USAGE File Extension .bak .evn .echo .drp .chm .ccm .ccd .domain . info .pdft .grf .g3d .pgr .plot . used in advanced IC engine models Run-time optional output file Any file containing pro-STAR commands Default input/output for miscellaneous problem data definitions File containing group and colour information for particles Default save file of current loop information Default pro-STAR model file (binary) Default input for SMAP-type data TGRID™ data output file Default input/output for NASTRAN™ data files Gambit™ data output file Default input/output for ANSYS™ node definitions Default output file Default input/output for PATRAN™ data files Look-up table file created when using PPDF chemical reaction models File containing participating media radiation data (binary) Neutral plot file Default output for STAR-CD problem data file (coded) File containing cell-to-processor mapping information used in STAR-HPC runs Default transient solution file (binary/direct access) Refinement data file used by the adaptive refinement commands (CMREFINE / CMUNREFINE) Residual history file for phase no.gen .loop .reu .grf .nas .lfb .inp .fvbnd .scl B-2 Usage Default input for GRID3D boundary data files Default input for GRID3D cell and vertex data files Default output for GENERIC data Default graph register data save file Default graph register ‘GET’ file Default combustion data file (binary).mdl .refi .node .pat .FILE TYPES AND THEIR USAGE Appendix B File Extension .out . 2 (used in Eulerian two-phase problems) Default residual history file (binary/direct access) Default input/output of residual histories for BINARY-CODED-BINARY file conversions Standard run-time output file Default output for scalar variable definitions (coded) Version 4.02 .prob .mdl .rsi .neu .pstt .run .ics .msh .inp .rsic .proc . X.usr) Vertex and/or cell number (as appropriate).trk . spline type (3I9) Up to 100 vertex numbers defining the spline (8I9) The format for couple definitions is: (file case. Z (global coordinates) (I9. region type (characters) (5(I9. patch number.unv .vfs . region number.trns .trkc . number of vertices.I2) The format for ASCII input to be used as post-processing data is: (file case. face number.14)) The format for boundary definitions is: (file case. cell number.set .trnc . 3(1X.uns . 6G16.vrml .bnd) Boundary number.02 B-3 .vrt Usage Default output for set definitions (written with the SETWRITE command) File for storing engine data (coded) Default input/output for spline definitions Default output for plotting-surface database (used to skip surface creation step in future plots) Default input for STL data files Default input file for droplet spray tables Default file for storing general table data Default input/output for particle/droplet tracks Default input/output of particle/droplet track data for BINARY-CODED-BINARY file conversions Default input for transient load data (coded) Default transient history save file (binary/direct access Default input/output for IDEAS™ (SDRC) universal file Fieldview™ data output file Default input/output for ASCII post data STAR file used for storing view factors Virtual reality data output file Default input/output for vertex definitions Default output for surface vertex definitions The format for vertex definitions is: (file case. Y.Appendix B FILE TYPES AND THEIR USAGE File Extension . number of cells (I8.G21. scalar value (I9. I5) Up to MAXNCP cell number/face number combinations 7(I9.srf .spl .vrt) Vertex number.usr .tabl .spd . Version 4.spl) Spline number.A) The format for spline definitions is: (file case.9).tbl .cpl) Couple number. 6X.1X).vrt . 1X.stl . . Units (SI) m2 W/mK kg/m3 m2/s Pa × s N W/m2 J/kg J/kg m kg kg/s kg/kmol Pa (N/m2) J/(kg × K) m/s N/m K (° Kelvin) s m2/s2 m2/s3 m/s m3 1/K Units (English) ft2 Btu/(hr × ft× F) lbm/ft3 ft2/s psi × s lb Btu/(hr × ft2) Btu/lbm Btu/lbm ft lbm lbm/hour lbm/kmol psi Btu/(lbm × F) ft/s lb/ft R (° Rankine) s ft2/s2 ft2/s3 ft/s ft3 1/R Version 4.Appendix C PROGRAM UNITS Appendix C PROGRAM UNITS Property AREA CONDUCTIVITY DENSITY DIFFUSIVITY DYNAMIC VISCOSITY FORCE HEAT FLUX HEAT OF FORMATION HEAT OF VAPOURIZATION LENGTH MASS MASS FLOW RATE MOLECULAR WEIGHT PRESSURE SPECIFIC HEAT SPEED OF SOUND SURFACE TENSION COEFFICIENT TEMPERATURE TIME TURBULENCE KINETIC ENERGY k TURBULENCE DISSIPATION RATE ε VELOCITY VOLUME VOLUMETRIC EXPANSION COEFF.02 C-1 . . This file is read by the Motif window manager when you log in or restart the window manager. Any changes made to this file do not take effect until either you log in again or you issue an xrdb command to re-read the X resource data base.geometry: Prostar. The easiest method is to put resource definitions in your . Any file can be used to set X resources. While default values for these resources are built into the program.geometry: Prostar*cmdForm1Widget. The only significance of the .height: Prostar*Prostar_Output_Text.Xdefaults file.height: Prostar*cmdForm2Widget.Appendix D pro-STAR X-RESOURCES Appendix D pro-STAR X-RESOURCES The Motif version of pro-STAR utilises standard X resources for defining the layout and look of its windows.Xdefaults include the full path to the .fontList: Version 4. for example. you will issue the command as follows: xrdb -merge .resources and put the resource definitions in that file. In this case.Xdefaults file if you are not in your home directory 2. you can override the defaults in two different ways: 1. create a file called PROSTAR. You could.defaultFontList: Prostar.Xdefaults file is that it is read automatically on start-up.02 D-1 . Typically.resources before running pro-STAR in order to activate those definitions The following describes some useful resource definition commands: Prostar*background: The default background colour for all pro-STAR applications The default foreground colour for all pro-STAR applications The size and position of the pro-STAR graphics window The font used for the pro-STAR graphics window menus The size and position of the pro-STAR output window The height of the output history portion of the pro-STAR output window The height of the input portion of the pro-STAR output text window The font used in the pro-STAR output window Prostar*foreground: Prostar.OutputWindow. you would have to issue the command: xrdb -merge PROSTAR. Buttons in panels are numbered starting from zero and are incremented by 1 from top to bottom and from left to right. The font used for the text section of the macro edit dialog The text foreground colour used in the macro edit dialog The text background colour used in the macro edit dialog Prostar*panel_name_B1. The foreground colour of button 1 in the user panel named panel_name.txt Geometry definitions are in the form of W × H + X + Y where W is the width (in pixels). Available font list names can usually be found by issuing the command: xlsfonts D-2 Version 4.02 .fontList: Prostar*macro_editor_text.background: The background colour of button 1 in the user panel named panel_name.foreground: Prostar*panel_name_B1.fontList: Prostar*macro_editor_text.background: The default background colour for all index cards (tabs) inside a STAR GUIde panel Prostar*GUIde_TABS.foreground: The foreground colour used in the pro-STAR output window Prostar*Prostar_Output_Text. Heights are also defined in pixels. and Y the distance from the top of the screen to the top of the window. H the height.background: Prostar*GUIde_INDEXCARD.foreground: Prostar*macro_editor_text. The font used for button 1 in the user panel named panel_name.background: The default background colour for all sub-index cards (sub-tabs) inside a STAR GUIde panel X colour names are usually (but not always) defined in the file: /usr/lib/X11/rgb.pro-STAR X-RESOURCES Appendix D Prostar*Prostar_Output_Text.background: The background colour used in the pro-STAR output window Prostar*panel_name_B1. Any panel button can be defined using the proper panel name and button number. X the distance (in pixels) from the left of the screen to the left side of the window. The first is finding out where you want the tool to be.background: Red Prostar*new_panel_B1.background: gray85 Prostar*new_panel_B1.fontList: -b&h-lucida-medium-r-normal-sans-24-*-*-*-*-*iso8859-1 Prostar*macro_editor_text.height: 700 Prostar*cmdForm2Widget. Follow this by issuing the xwininfo command from an X-window to get the necessary numbers.fontList: -adobe-courier-bold-r-normal--18-180-75-75-m-110iso8859-1 Prostar*Prostar_Output_Text.foreground: blue Prostar*macro_editor_text.fontList: -adobe-courier-bold-r-normal--18-180-75-75-m-110iso8859-1 Prostar*macro_editor_text. This is especially useful if you have a number of favourite tools that you open each time and can make pro-STAR open them every time via the PROINIT file.fontList: -adobe-courier-medium-r-normal--12-120-75-75-m-70iso8859-1 Prostar*new_panel_B2.geometry: 800x800+480+0 Prostar. There are two steps in doing this. For example: ibm3<68>xwininfo Version 4.background: Green Prostar*new_panel_B2.defaultFontList: -adobe-helvetica-bold-r-normal--14-140-75-75-p-82iso8859-1 Prostar.02 D-3 .Appendix D pro-STAR X-RESOURCES The following shows a sample of resource definitions that could be used with pro-STAR: Prostar*background: Prostar*foreground: paleturquoise3 black Prostar. in pro-STAR If you run the XMotif version of pro-STAR.height: 70 Prostar*Prostar_Output_Text. etc.background: skyblue To customise the opening locations of Tools. it is possible to arrange for tools to open in repeatable locations. Lists.foreground: blue Prostar*Prostar_Output_Text.geometry: 1000x870+0+0 Prostar*cmdForm1Widget.OutputWindow. run pro-STAR and then place (and optionally resize) the tool to get the desired effect. To this end. The above has been tested and works so far on SGI and IBM machines. The second step is to feed this information to pro-STAR via Xresources. On some systems. GEOMETRY is the location of the window as found from the previous command. -geometry 630x590-55-52. In this case. capitalisation must be kept. pro-STAR should respond correctly. Once this line has been added to the file. The name is enclosed in quotes in the first line of output. This gives the width and height as well as the location. xwininfo: Window id: 0x54007c2 "Check Tool" Absolute upper-left X: 587 Absolute upper-left Y: 374 Relative upper-left X: 0 Relative upper-left Y: 0 Width: 630 Height: 590 Depth: 8 Visual Class: PseudoColor Border width: 0 Class: InputOutput Colormap: 0x3d (installed) Bit Gravity State: ForgetGravity Window Gravity State: NorthWestGravity Backing Store State: NotUseful Save Under State: no Map State: IsViewable Override Redirect State: no Corners: +587+374 -63+374 -63-60 +587-60 -geometry 630x590-55-52 This gives us two pieces of information.pro-STAR X-RESOURCES Appendix D xwininfo: Please select the window about which you would like information by clicking the mouse in that window. for this case it is Check Tool.Xdefaults in your home directory.02 . The usual way is to edit file . Other D-4 Version 4. Others may require you to log out and log in again or issue some variant of the xrdb command. the name and the location. add the following line: Prostar*CheckTool*Geometry: 630x590-55-52 This line is made up as follows: Prostar*NAME*Geometry: GEOMETRY where: NAME is the name of the window stripped of all spaces. The location is given in the last line. restarting pro-STAR will suffice. Version 4. A suitable PROINIT file will be: opanel tool$check Make sure that the PROINIT file is in your current directory or that it is pointed to by the STARUSR environment variable.02 D-5 .Appendix D pro-STAR X-RESOURCES machines may work with minor variations. . Appendix E USER INTERFACE TO MESSAGE PASSING ROUTINES Appendix E USER INTERFACE TO MESSAGE PASSING ROUTINES Some user coding might need access to message passing routines when used in a parallel run. This appendix lists the parallel message passing calls that may be used within the user coding.02 E-1 . Version 4.GLO) Parameters LOGICAL LOC — local value (input parameter) LOGICAL GLO — global value (output parameter) LGLAND — Global AND operation Synopsis SUBROUTINE LGLAND (LOC.GLO) Parameters LOGICAL LOC — local value (input parameter) LOGICAL GLO — global value (output parameter) 1. Type REAL becomes DOUBLE PRECISION in double precision runs. IGSUM — Global Integer Summation Synopsis INTEGER FUNCTION IGSUM (LOCSUM) Parameters INTEGER LOCSUM — local value Returns integer sum of LOCSUM GSUM — Global Floating Point Summation Synopsis REAL1 FUNCTION GSUM (LOCSUM) Parameters REAL1 LOCSUM — local value Returns floating point sum of LOCSUM DGSUM — Global Double Precision Summation Synopsis DOUBLE PRECISION FUNCTION DGSUM (LOCSUM) Parameters DOUBLE PRECISION LOCSUM — local value Returns double precision sum of LOCSUM LGLOR — Global OR operation Synopsis SUBROUTINE LGLOR (LOC. 02 . E-2 Version 4. Type REAL becomes DOUBLE PRECISION in double precision runs.USER INTERFACE TO MESSAGE PASSING ROUTINES Appendix E GMAX — Global MAX operation Synopsis REAL1 FUNCTION GMAX (LMAX) Parameters REAL1 LMAX — local value Returns global MAX of LMAX GMIN — Global MIN operation Synopsis REAL1 FUNCTION GMIN (LMIN) Parameters REAL1 LMIN — local value Returns global MIN of LMIN IGMAX — Global MAX operation Synopsis INTEGER IGMAX (ILMAX) Parameters INTEGER FUNCTION IGMAX — local value Returns global MAX of ILMAX IGMIN — Global MIN operation Synopsis INTEGER FUNCTION IGMIN (ILMIN) Parameters INTEGER IGMIN — local value Returns global MIN of ILMIN 1. The default is to use a ‘CHECK’ sub-directory. Collect and save data from previous crashed run only.0. The default is off. Sun Grid Engine or Torque.]]]] Options -version -abort -batch -case=casename -chktime=minutes -chkdir=directory -chkpnt -collect -dp -devtool="program" -fork -g -kill Show STAR version information. This requires STAR-NET 3. PBSPro.3 or later to be installed. The use of this option is advised on sequential runs only. since it will merge the case’s results. Compile ufile source code. Version 4.. Enable STAR controlled check-pointing at a regular interval in minutes for fault tolerance. Generate script for running batch job.Appendix F STAR RUN OPTIONS Usage Appendix F STAR RUN OPTIONS Usage star [options] [node1 [node2 [node3 [. Select directory for storing the check-pointed data. This option may be useful for visualising fields while STAR is still executing in parallel. See also option "-devtool". Perform manual check-pointing of STAR results now. LSF. with the exception of combustion problems which use either STAR/KINetics or the Complex Chemistry model. Useful if run is to be submitted via a batch-queuing system like IBM Loadleveler. which includes patch number. so that the user may employ a debugger to perform a step-by-step analysis of the coding in the user subroutines. Current default is single precision. For parallel runs only LAM MPI and MPICH are fully supported with Totalview. Enable the use of fork() for starting local external moving mesh codes and NFS-based communications. OpenPBS.. Select the case name manually. Send SIGKILL to terminate STAR immediately. Make STAR-CD run in double precision arithmetic. in which case STAR-CD will execute in double precision.02 F-1 . This option is not needed in general. Attach a development tool like a debugger to a STAR-CD run. Send SIGABRT to stop STAR after the current iteration or time step. The "-save=" option can be used to make a new save list. Use this option to extract execution time information from the run.dat" -save="file2.dat" or -save="file1. i. if it contains any syntax mistakes.02 . Compile user coding and build new plugable object only. Files that should not be merged should be left out from this option. i. On a parallel run. Ideally. Useful to verify if user coding compiles.dat file2. these files should be formatted into two columns: the first column containing an index numeral that can be ordered (i. Forces geometry decomposition (if applicable). Wildcards “*” and “?” are accepted. Example: -save="file1. and the second column containing the physical quantity of interest. pro-STAR cell number).e.e. user coding compilation and copying of input files (if applicable) before STAR-CD starts to execute. Disable memory based scratch files. Continue the run from an existing restart file by resetting the restart flag in the problem file. where the variable will be set on all processes. Example: star -set MYVAR="on" Enable printing of detailed timing data. Disable the recalculation of radiation view factors. Disable saving of results by using an empty save list.. events preparation (if applicable).. these files will be merged into a single file. Ignore user coding in the "ufile" directory.dat" -set variable="value" Set environmental variable to a value. especially on a parallel run. Specify additional output files for treatment as results.STAR RUN OPTIONS Options -nolookahead -noramfiles -norecalc -norestart -nosave -noskip Appendix F -noufile -restart -save="filelist" Disable look ahead for socket-based external moving mesh code communications. Please note that the use of this option entails a performance penalty. the run’s results will not be influenced by the actual user coding. -timer -toolchest -ufile F-2 Version 4.e. Build new STAR toolchest from plug-in tools. Disable restart (if selected in the problem file) by resetting the restart flag. Appendix F STAR RUN OPTIONS Parallel Options -uflags="flags" -ulib="librarylist" -watch Select additional flags for compiling user coding. This option gives the user added flexibility in using other compiler options that may not be listed in installation scripts.dat" -decomp Run geometry decomposer only. STAR will decompose the mesh in 5 parts using 2 cpu’s on machine "host1" and 1 cpu on machine "host2". Example: -decomphost="host1. Example: -copy="file1. In particular. Specify precompiled user coding libraries and/or some additional dynamic shared objects required by user coding. Useful to check the outcome of the decomposition if it has to satisfy certain criteria.dat" or -copy="file1. for the Parmetis decomposition option more than two cpu’s (whether or not on the same machine) should be used. Version 4.e. The daemon itself and the StarWatch GUI still need to be run separately Parallel Options -copy="filelist" Specify additional input files for copying to domains on a parallel run.2 host2" 5 In the above. The number of cpu’s to decompose the mesh can be smaller than the number of requested partitions.02 F-3 . host1:host2:…).dat" -copy="file2. -decomphost=hostlist Selects host(s) for running the decomposer (i. Enable connection to the StarWatch daemon.dat file2. above. The abbreviations shown in parentheses can be used instead. the mesh is treated as if it was just one single material domain) is decomposed in a single (Cartesian) direction in which the model is largest. parmetis (p): Parallel version of the Metis family of algorithms. Example: -decompmeth=g F-4 Version 4. each material domain will be decomposed in turn. in which case the default becomes ‘sets’. metis (x): The mesh will be partitioned with Metis. automatic (a): The decomposition will uniformly divide the number of cells between the intended number of processes. second column contains the process number to which the cells are going to be assigned. geometric (g): The entire mesh (i. based purely on pro-STAR cell numbering.e. Their individual meanings are: optimised (o): The decomposition will be read from file <casename>.STAR RUN OPTIONS Parallel Options -decompmeth=method Appendix F Select one of the decomposition methods listed below. By default.02 . each material domain will be decomposed in turn. ometis (y): Same as above. By default.. except when the model contains events. This option is to be used in conjunction with option ‘-decomphost’. manual (m): The decomposition is done according to cell types. as it has been defined in pro-STAR. as they have been defined in pro-STAR sets (s): The decomposition is read from a . a built-in graph-handling library.set file. composed of two columns: first column contains cell numbers. The default is ‘metis’ decomposition.proc. Parmetis executes the domain decomposition step in parallel and requires less memory than the Metis algorithm. but with a lower memory footprint and higher execution time. Parmetis calculates decompositions of similar quality to sequential Metis. proc). this file can be manipulated from within pro-STAR in the usual manner or it can be used to repeat the same decomposition with. Automatic selection of the MPI implementation using the vendor order shown below.e. the vertex movement may be specified relative to a fixed vertex). This is the default behaviour which can be changed by supplying one of the flags below: F-5 -distribute -loadbalance -mergehost=hostlist -mpi=auto Version 4. Selects host for merging results (i. Select load balancing taking into account the relative speeds of the hosts. for example. the vertices on each geometry file will be numbered from 1 to the local maximum number. except for moving mesh and liquid film cases where the default is not to compress. Please see your Systems Administrator for details. outsets: this option will trigger the creation of a sets file in the case’s directory. a different version of STAR in conjunction with the ‘-decompmeth=s’ decomposition option.02 . novc: Disable vertex compression.sets). each set will contain the cells that belong to a certain subdomain.g. The vertex numbering may be important for the mesh motion operation (e. can be loaded into pro-STAR for the user to visualise the decomposition (with command RDPROC) or it can be used to repeat the same decomposition with. Please see your Systems Administrator for details. as set up at the time when STAR-CD was initialised. In this file (<casename>. a different version of STAR in conjunction with the ‘-decompmeth=o’ decomposition option. host1:host2:…). this option will trigger the creation of a cell assignment file in the case’s directory.Appendix F STAR RUN OPTIONS Parallel Options -decompflags="flags" Special options for the domain decomposition step: vcom: Compress vertex indices on each geometry file. if not compressed. the vertices will retain their original numbering from the un-decomposed mesh. Example: -decompflags=”outproc” Select distributed data parallel runs using local scratch disks. The default action is to compress vertices. this file (<casename>. if compressed. for example. as set up at the time when STAR-CD was initialised. outproc: If chosen. Instead this is automatically determined from the resources assigned by the user or the resource manager. This over rides HPC_SCRATCH settings and must be unique for each running case. Select the scratch directory path to use on all nodes for distributed data runs.02 . If STAR options are required they need to be specified before the nodes list. Select non-default network for message passing protocol using alternative host names. Use this option to supply additional flags as expected by the MPI implementation. This also disables saving of results. Please note that any updates to these files must be performed manually and the data can be manually collected using the "-collect" option at the end of the runs.STAR RUN OPTIONS Resource Allocation -mpi=os -mpi=gm -mpi=hp -mpi=intel -mpi=ra -mpi=scampi -mpi=score -mpi=sgi -mpi=lam -mpi=mpich -mppflags="flags" Appendix F -mpphosts -nocollect -nocopy -nodecomp -noshmem -scratch=directory Select Operating System Vendor’s MPI Select MPICH-GM (Myricom GM MPI) Select HP MPI Select Intel MPI Select RA-MPICH (Rapid Array MPI) Select ScaMPI (Scali MPI) Select SCore MPI Select SGI Itanium MPI Select LAM MPI Select MPICH (ANL/MSU MPI) Select additional flags for message passing protocol. Do not decompose the computation mesh on a parallel run and use the last decomposition instead. The "-copy=" option can be used to make a new copy list. The user should not need to use this option in general. Please see your Systems Administrator for details. as set up at the time when STAR-CD was initialised. Disable data collection at the end of a distributed data parallel run. Disable shared memory communications for parallel runs on a single node. Resource Allocation The user does not select sequential or parallel STAR runs directly. In general. Disable copying of input files by using an empty copy list. the user should not need to use it. It is possible to restart using the data already distributed to the local scratch disks. F-6 Version 4. np” parameter is not supplied. Its value is normally set in the software initialization file (software. The default is to overload the STAR master CPU with the external moving mesh code. when one is being used.02 F-7 . where “np” is the number of processes to use. The node is specified in the format “hostname. The local host will be assumed if the “hostname” is not specified and a single process will be used if the “. The number of STAR domains plus one extra process is needed in the resource line.ini) to cater for site-specific STAR solver options that are always used. Select nodes to use for running STAR in a file. the software administrator can set things up so that ordinary Version 4. The nodes to use for running STAR. Default Options The environment variable STARFLAGS can be set to include some default STAR options that will be processed before any command line options. Another example is: STARFLAGS=-set GTIHOME=/users/netapps/gt GTISOFT_LICENSE_FILE=27005@heraclitus Using STARFLAGS. if STARFLAGS=-mpi=mpich the user can still use LAM MPI as follows: star -mpi=lam However. Examples are: STARFLAGS=-dp STARFLAGS=-set VARIABLE="Some Value" STARFLAGS=-mpi=mpich -noshmem -distribute -timer The user can reset STARFLAGS manually or use a different .np”. Thus. but only if an alternative option exists.Appendix F STAR RUN OPTIONS Default Options -mvmeshhost=host -nodefile=file -nooverload node1 node2 node3 Select additional resource for running external moving mesh code. This can be specified on a single line or multiple lines.ini file to change its value. if STARFLAGS=-dp this setting cannot be modified because a single-precision option is not available at the command line. The options defined in STARFLAGS are always processed first and can be over-written by additional command-line options. Disable overloading of the STAR master processor with the external moving mesh code. An important aspect of this work is STAR-CD’s integration with MPIs that support various network interconnect devices. Running under IBM Loadleveler using STAR-NET To run STAR-PNP under Loadleveler: 1.02 . interconnect latency.STAR RUN OPTIONS Cluster Computing Appendix F users need to do less work. Note also that the PBSPro and Torque are only supported in OpenPBS compatibility mode. lightweight tool for running applications in sequential and parallel modes under a batch environment using a resource manager. Therefore.x versions (which only work with STAR-CD in parallel mode).0. you must install STAR-NET 3. Users are advised to contact the relevant system vendors to check whether a particular combination of MPI implementation and network interconnects works with STAR-CD. It is a completely new design.x compliant plug-ins. Batch Runs Using STAR-NET STAR-NET 3.x is a new. OpenPBS. interconnect bandwidth and file system performance. PBSPro.sh script by specifying the -batch option: star -batch <options> F-8 Version 4. Other examples are to make everybody run in double precision. the IBM Loadleveler. Concise guidelines for running under each system are given below. CD-adapco have been actively working with computer hardware and software vendors to ensure that STAR-CD takes full advantage of progress in cluster technology. such as MPI performance. it is not possible to test all MPI/interconnect combinations and to measure their performance. By checking which network interconnect devices are supported by each MPI.x in order to run in batch mode or to use any of the above resource mangers. etc. Users can type star -h to check the available MPI options for the port they are using prior to issuing one of the "star -mpi=" commands in their session window. Currently. Due to the extensive range of cluster configurations and the rapid developments in cluster technology. users can determine whether STAR-CD works with a particular MPI/interconnect combination. STAR-CD’s performance on a cluster is influenced by numerous factors. not compatible with the previous STAR-NET 2. LSF. We have been working with our hardware and software partners to provide benchmark data on various clusters and such data are available on CD-adapco’s web site. Create a batch. Cluster Computing Cluster computing is widely adopted by STAR-CD users and typically consists of computing nodes connected by network interconnect devices such as Gigabit Ethernet. Myrinet and InfiniBand. assuming prior configuration as detailed in the Installation and Systems Guide. Sun Grid Engine and Torque resource managers are supported through STAR-NET 3. to always use the -distribute option. 3.02 F-9 .sh script.Appendix F STAR RUN OPTIONS Batch Runs Using STAR-NET where <options> represents all the normal STAR-PNP flags for your job. as described in the sections above.sh script by specifying the -batch option: star -batch <options> where <options> represents all the normal STAR-PNP flags for your job. Note that you cannot assign a node list for Version 4. so you will need to enable application-level check-pointing by STAR-PNP as follows: star -batch <options> -chktime=60 llsubmit batch.o123 • Terminate job number 123 under Loadleveler llcancel 123 • Use the built-in GUI interface for submitting and monitoring jobs xloadl Running under LSF using STAR-NET To run STAR-PNP under LSF: 1. The following shows the most useful settings: # # # # @ @ @ @ node_usage class node total_tasks = shared = = 3 = 8 The above requests 3 nodes and a total of 8 CPUs for running the batch job. The llsubmit command does not support automatic restarts and checkpointing.sh The llsubmit command does not allow any resource selection and so this must be specified correctly in the batch. Create a batch. as described in the sections above. Submit your job using the llsubmit command. For example: star -batch <options> -chktime=60 llsubmit batch. 2.sh Other useful Loadleveler commands: • Show all my Loadleveler jobs llq -u username • Continuously monitor the output of job number 123 tail -f batch. Note that you cannot assign a node list for resource allocation in batch mode as this will be performed automatically by Loadleveler. 4 -r -k "CHECK 60" batch. 2.4 batch. as described in the sections above.02 .STAR RUN OPTIONS Batch Runs Using STAR-NET Appendix F resource allocation in batch mode as this will be performed automatically by LSF.sh script by specifying the -batch option: star -batch <options> where <options> represents all the normal STAR-PNP flags for your job. Submit your job to the queue using the bsub command.sh It is recommended that you always enable check-pointing and automatic restarts to allow time-windowing/high-load-enforced job migration to work. For example.sh Other useful LSF commands: • Show all my LSF jobs bjobs • Continuously monitor the output of job number 123 peek -f 123 • Terminate job number 123 under LSF bkill 123 • Use the built-in GUI interface for submitting and monitoring jobs xlsbatch Alternatively.sh (b) To submit to queue starnet requesting 2 to 4 processors with LSF-controlled automatic restarts and enabling check-pointing every 60 minutes: bsub -q starnet -n 2. Running under OpenPBS using STAR-NET To run STAR-PNP under OpenPBS: 1.4 -r -k "CHECK 60" batch. Submit your job to the queue using the qsub command. 2. Create a batch. For example: (a) To submit to queue starnet requesting 2 to 4 processors: bsub -q starnet -n 2. (c) To submit to a subset of hosts: bsub -q starnet -m "host1 host2 host3" -n 2. Note that you cannot assign a node list for resource allocation in batch mode as this will be performed automatically by OpenPBS. command starnet can be used to display a brief summary of the current LSF status. to F-10 Version 4. Running under PBSPro using STAR-NET PBSPro is supported in OpenPBS compatibility mode. so you will need to enable application-level check-pointing by STAR-PNP as follows: star -batch <options> -chktime=60 qsub -q starnet -l nodes=3:ppn=2 batch.02 F-11 . For example: (a) To submit to parallel environment starnet requesting 2 to 4 processors: qsub -pe starnet 2-4 batch. 2. Submit your job to a queue using the qsub command.Appendix F STAR RUN OPTIONS Batch Runs Using STAR-NET submit to queue starnet requesting 3 nodes with 2 processors each: qsub -q starnet -l nodes=3:ppn=2 batch. as described in the sections above. Create a batch. OpenPBS does not support automatic restarts and check-pointing.sh.sh 3.sh Other useful OpenPBS commands: • Show all my OpenPBS jobs qstat -u username • Continuously monitor the output of job number 123 tail -f batch. Running under SGE using STAR-NET To run STAR-PNP under Sun Grid Engine: 1. This means that only OpenPBS features are supported (see the description above). Note that you cannot assign a node list for resource allocation in batch mode as this will be performed automatically by Sun Grid Engine.o123 • Terminate job number 123 under OpenPBS qdel 123 • Use the built-in GUI interface for submitting and monitoring jobs xpbs Please note that only the OpenPBS features of PBSPro and Torque are supported.sh script by specifying the -batch option: star -batch <options> where <options> represents all the normal STAR-PNP flags for your job.sh (b) To submit to a subset of queues: Version 4. Other useful SGE commands: • Show all my Sun Grid Engine jobs qstat -u username • Continuously monitor the output of job number 123 tail -f batch. so you will need to enable application-level check-pointing by STAR-PNP as follows: star -batch <options> -chktime=60 qsub -pe starnet 2-4 -ckpt starnet batch. Running under Torque using STAR-NET Torque is supported in OpenPBS compatibility mode.3 do not support automatic restarts when the master host fails. This means that only OpenPBS features are supported (see the description above).02 .STAR RUN OPTIONS Batch Runs Using STAR-NET Appendix F qsub -pe starnet 2.queue3 -ckpt starnet batch.o123 • Terminate job number 123 under Sun Grid Engine qdel 123 • Use the built-in GUI interface for submitting and monitoring jobs qmon Alternatively.4 -q queue1. F-12 Version 4. command starnet can be used to display a brief summary of the current SGE status.sh. Sun Grid Engine supports automatic restarts but not check-pointing.sh 3.sh Please note that Sun Grid Engine versions earlier than 5.queue2. D. 1989.. 1 and Vol. “Computer Program for Calculation of Complex Chemical Equilibrium Compositions and Applications. New York.J. pp. ‘On upstream differencing and Godunov-type schemes for hyperbolic conservation Laws’. Publ. P. “The Dynamics and Thermodynamics of Compressible Fluid Flow — Vol. NASA Lewis Research Center. Lax. NASA Ref.M. [6] [7] Version 4. 2”. Shapiro A. Part I. and McBride B. and Miller J. ‘The Chemkin Thermodynamic Data Base’.W. 1983. Harten. B. 1311. Analysis”. “Computer Program for Calculation of Complex Chemical Equilibrium Compositions and Applications.02 G-1 . NASA Lewis Research Center. Part II.A. Ronald. 1990. “Elements of Gas Dynamics”. NASA Ref. and Roshko A. SAND87-8215B. J. 1957. 1953. and Van Leer. 1996. SIAM Rev. John Wiley & Sons.H. Liepman H. A. 1994.. NASA Lewis Research Center. New York. 25. Users Manual and Program Description”. 35-61. Gordon S.Appendix G BIBLIOGRAPHY Appendix G BIBLIOGRAPHY [1] [2] [3] [4] [5] Kee R. Rupley F. J. McBride B. and Gordon S.. Sandia Report No. “CET89 — Chemical Equilibrium with Transport Properties”. Publ. 1311. . 4-25. 5-4. axisymmetric B background colour 2-32 material. See flow. boundaries for 4-36 all set selection option 2-21. attachment autoignition (double-delay model) 8-37 to 8-39 average nuclear radius 11-7 axis of rotation 12-4.INDEX INDEX Commands are listed in a separate index immediately following this one A abbreviations of commands 16-1 absorption coefficient 7-4 absorptivity of baffle 4-26 thermal 4-25 of wall 4-22 solar 4-21 thermal 4-20 accuracy numerical 1-5 temporal 1-14 view factor 7-5 adaptive mesh refinement. 4-27 to 4-32 anticyclic 4-29 partial 4-30 defined by GT-POWER 4-9 defined by tables 2-24. A-2 selection 4-3 symmetry 1-3 types 4-5 visualisation 4-41 boundary conditions 1-11 attachment 4-38 to 4-39 displaying 12-30 baffle 4-23 to 4-27 for solar radiation 4-26 cyclic 1-3. 6-5 radiation 4-25 side numbering 4-24 thickness 3-18 transparent 4-26 batch mode 2-34 beams 7-6 black and white printing 17-22 Version 4. 3-14 list 4-3 location 1-11. 5-11 compress 4-7 default (region no. See boundary conditions. 1-12. 10-1 for cavitating flows 11-5 for compressible flow 3-9 for free surface flows 11-1 for liquid films 13-6 for rotating frames 12-6 for subsonic compressible flow 3-9 1 . 17-19 block set 2-21. See mesh. 12-8 axisymmetric flow. in chemical reactions 8-17 background fluid 13-3 baffle 4-23 to 4-27 conducting 3-18 expanding 3-18 in restart after mesh changing 5-17 porous 4-24. 4-3 angle internal 1-5 warp 1-5 angular velocity 12-1. 4-1 to 4-5 maximum number of 2-18 modifying 4-2 monitoring behaviour 5-3 monitoring regions 4-40 notional 1-4 region 4-1 changing type 4-2. See cavitation boundary cells 1-4 defining 4-2 layer 1-6 in compressible flow 3-10 turbulent 1-7. 12-8 defined by user subroutines 14-16 animation 2-32 anode 8-33 append mode 2-13 aspect ratio cell 1-5 to 1-6 patch 7-6 atomisation models 9-1 attachment boundaries. 4-3 aeroacoustics 13-3 aerodynamics problems. 4-7 baffles 4-27 free-stream 4-33 inlet 4-10 non-reflective 4-19 outlet 4-12 pressure 4-14 Riemann 4-37 stagnation 4-16 transient wave transmissive 4-35 wall 4-22 defined by user subroutines 4-7. A-2 boiling. 14-5 defined using load steps 5-6 to 5-14 degassing 4-40.02 black body 4-20 blending factor 14-19. adaptive refinement add set selection option 2-21. 0) 4-7 defining 4-5 set 2-21. 15-2. 4-14 radiation 4-39 to 4-40. See velocity. 14-6 for cavitating flows 11-9 for free surface flows 11-4 radial equilibrium 4-9 on pressure boundaries 4-12. 4-12 to 4-14. 14-6 outflow 1-11. 11-9 steady-state flows 11-6 temperature calculation 11-8 vapour properties 11-7 CEA (Chemical Equilibrium with Applications) program 8-3 cell 1-2 attachment 12-18. characteristic check tool 3-5 checking model and problem data 15-1 results 1-20 chemical reaction. 12-4. See flow. 4-32 to 4-34. D-2 foreground D-1.Index for supersonic flow 3-9 for transonic flow 3-10 free-stream 1-12. 2-41 Version 4. A-2 volume 3-22 shape 1-4 shape changing 5-15 size 1-6 table 3-1 to 3-3 compress 3-3 editor 3-1 to 3-3 radiation 7-8 number 3-2 porosity 6-1 tool 3-3 type 3-3 change fluid type 12-23 change grid (CG) operation 12-9 characteristic length. 14-6 wall 4-19 to 4-23. 4-14 to 4-16. 7-8 Riemann 1-12. See length. 12-23 to 12-28 data 17-3 detachment 12-23 to 12-28 face boundary 4-1 matching 4-29 index 3-3 interface 12-18 layer addition 12-14 2 . 11-6. 4-27 table input 2-24 to 2-31 time-varying 5-4 transient wave transmissive 1-12. D-2 options 2-4 palette 3-2 table index 3-2 colour tool 17-22 combustion. 4-10. 4-12 outlet 1-11. characteristic velocity.02 C calculations. 11-8 initialisation 11-8 solution algorithms 1-13. 4-11 to 4-12. 4-9. 3-14 number of 15-1 plot 2-23 properties 3-1 set 2-21. 4-16 to 4-19. 4-34 to 4-36. buoyancy driven byte ordering 16-1 removal 5-17. 14-6 for solar radiation 4-20 in turbulent flow 3-12 See also wall buoyancy 1-9 See also density buoyancy driven flow. 3-4 maximum number of 2-18 monitoring behaviour 5-3 near-boundary 1-4 near-wall 3-12. See reaction CHEMKIN 8-11 clearing entire geometry 17-14 coal combustion 8-41 to 8-47 default models 8-42 inlet mass fractions 8-44 coal particle size distribution 8-45 colour background 2-32. 17-2 input 2-13 echo 2-19 output 2-13 number of lines 2-19 commands 2-36. See reaction and coal combustion command abbreviations 16-1 arithmetic in A-1 conventions A-1 help A-3 history 2-13. checking 1-20 catalytic converters 8-1 cathode 8-33 cavitation 11-5 to 11-10 defined by user subroutines 14-11 in free surface flows 11-3. 2-19. 12-14 list 2-24. D-1. 3-13. 14-6 stagnation 1-12. 14-6 for rotating reference frames 12-1. 14-6 plots of 4-8 prescribed flow 1-11 pressure 1-12. 12-9 symmetry 1-12. 4-36 to 4-38. 14-6 inlet 4-9 to 4-11. 14-5 non-reflective 1-12. 17-19 dependent variable in tables 2-27 initialisation 1-10. 14-18 for Lagrangian multi-phase flow 9-10 for LES turbulence models 3-15 for pseudo-transient calculations 5-2 crank angle 9-9 cursor select 2-19. See near-wall. 13-6. A-2 customisation of pro-STAR 2-18. 16-1 cyclic boundary pair. 2-9 discrete fourier transform (DFT) algorithm 4-18 discrete transfer/ordinates radiation. 8-19 reference 3-21 in buoyancy driven flow 4-14 under-relaxation 1-15. working 2-3. normal dimensionless.Index compressibility 3-9 compressible flow Courant number 5-9 model setup 3-9 to 3-11 outlets 1-11 to 1-12 pseudo-transient approach 5-1 stagnation boundaries 4-14 transient. 13-7 user subroutines 9-1 to 9-3. 4-42 Version 4. dimensionless normal distance and y+ values distributed resistance 6-1. See radiation discretisation error 1-6. 12-23 in porous media 6-2 to 6-3 corrector step tolerance 1-14 couple set 2-21. cyclic set list 4-31 monitoring 1-19 printout 15-3 differencing schemes 15-2 for free surface flows 11-2 for steady-state runs 5-2 for transient runs 5-11 for use with DES turbulence models 3-15 for use with LES turbulence models 3-15 diffusion reaction system 8-1 diffusivity characteristic 1-14 molecular. A-2 set selection 9-6 track list 9-7 transfer to/from liquid films 13-5. A-2 couples across cyclic boundaries 4-29 Courant number 5-9. 3-9 defined by user subroutines 14-8 in aeroacoustic analysis 13-4 in buoyancy driven flow 3-20 in free surface flows 11-3 in PPDF scheme reactions 8-4. defined by user subroutines 14-8 porous 6-4 directory. See boundary conditions. 15-2 user subroutines 14-8 divergence 2-6. 2-7 double precision mode 1-18 drag coefficient 14-19 force 14-14 droplet age 9-7 collision models 9-1 defined by user subroutines 14-12 diameter distribution function 9-1 defined by tables 2-26 gravitational effect 3-21 information 9-8 mass transfer 14-13 momentum transfer 14-13 number density 14-12 positions 9-7 reading data 9-5 set 2-21.02 3 . boundaries for 4-34 compression wave 4-32 condensation to liquid films 13-6 conduction thickness 3-19 conduction through baffles 4-25 conductivity defined by user subroutines 14-6 in chemical reaction problems 8-17 in multi-component mixing 13-3 connectivity 12-18 control keys A-4 controlling STAR with StarWatch 17-17 convergence 1-19 in steady-state calculations with SIMPLE 1-16 in transient calculations with SIMPLE 1-17 rate of 4-13 coordinate system in attachment boundaries 12-19. 14-12 to 14-13 volume 9-10 D deleting entire model 17-14 density at Riemann boundary 4-37 calculation 1-9. 1-21 schemes 1-21 temporal for cavitating flows 11-9 for DES turbulence models 3-15 for free surface flows 11-4 for LES turbulence models 3-15 with the SIMPLE algorithm 1-18 time 5-11 volume 1-3 distance. 17-10 save model 17-2. 17-2 monitoring engineering data 5-3 output 2-7 panels 16-5 param. 1-21 recovery 2-20 round-off 1-18 splitting 1-13 escape surfaces 7-2. 1-15 numerical discretisation 1-6. 17-1 to 17-12. 7-4 Eulerian multi-phase flow boundaries 10-1 interphase 10-2 model setup 10-1 to 10-4 phase-escape boundary 4-40 response coefficient 14-14 user subroutines 14-14 evaporation from liquid films 13-6 event steps cell attachment 12-22 cell inclusion/exclusion 12-28 cell removal/addition 12-14 deleting 12-12 listing 12-12 modifying 12-12 moving mesh 12-9 moving pistons 12-13 reading 12-12 regular sliding 12-18 turning off 12-30 writing 12-12 exhaust gas recirculation 8-11. 17-10 system command 2-18 write geometry file 17-5. 14-10 in PPDF scheme reactions 8-19 stagnation 3-11 temperature dependence 14-7 environment variables 17-12 equations of state 1-9 error messages 2-19 sweep limits 1-14. B-1 to B-3 boundary 17-3 cell 17-3 coded 17-3 command 17-10 data repository 17-5 droplet data 9-5 echo 17-2 editing 17-11 engines 9-9 event steps 12-12. 17-10 write problem file 17-6. 7-4 of wall 4-22 thermal 4-20.prp 17-13 plot 17-4 problem 2-6. 12-19 format of B-3 geometry 17-5 load step 5-9 macros 16-6 manipulating 17-9 mapping 5-15 model 2-4. 8-17 exhaust valve 5-11 expansion wave 4-32 exposure of baffle 4-26 of wall 4-20.02 . 17-10 files 2-36. 4-22 F facets 1-4 4 FASTRAC 7-1 boundary conditions 7-2 escape boundaries 7-5 patches 7-2 symmetry and cyclic boundaries 7-5 user subroutines 7-6 view factors 7-3 with moving mesh 7-7 favourites menu 2-17 file menu 2-16 case name 17-1 edit file 17-10 model title 2-19 resume 17-10 resume from 17-2 resume model 17-2 save as coded 17-3.Index E emissivity at escape boundaries 4-39 at radiation boundaries 4-39 of baffle 4-26 solar 4-26 thermal 4-25. 7-4 with FASTRAC 7-2 engine data 9-9 enthalpy defined by user subroutines 14-7. 7-1. 17-6 PRODEFS 16-1 PROINIT 16-1 reaction mechanism 8-11 relationship between 17-7 residual 17-6 restart 2-7 scalar properties 13-3 scene 17-23 set-up 16-1 solution 17-5 STAR-CD 3. 7-1.2x equivalents 17-6 temporary 17-14 Version 4. 3-10 residuals 3-10 turbulent 3-12 unsteady 1-10 fluid background 13-3 injection 3-21 to 3-22 defined by user subroutines 14-10 mixture 13-1 non-Newtonian 3-11 properties 13-3. modifying 5-15 graph menu 2-17 graphics driver 2-3 group number 3-2 GT-POWER 4-9 H hard copy 17-21 heat conductivity defined by user subroutines 14-6 in chemical reaction problems 8-17 in multi-component mixing 13-3 transfer coefficient 3-17. See ideal gas law geometry. See compressible flow cyclic 5-4 free surface. 7-6 film stripping 13-5. 1-15. 8-31 AKTIM 8-33 to 8-36 for simulations involving cell layer removal 12-18 imbalance 7-5 independent variables in tables 2-27 inflow at outlet boundaries 1-11 INFO button 2-22 initial conditions 1-10. 15-2 stream 15-2 multiple 3-5 font size 2-33 fonts D-1. 5-9 transonic 1-11. 14-15 advanced ICE models 8-24. 3-9 mesh at inlet boundaries 4-10 transient 1-13 to 1-15 analysis controls 5-4 to 5-14 output controls 5-5. See cavitation chaotic 5-4 compressible. See free surface flow impingement 3-15 inviscid 4-19 enthalpy 3-10 non-Newtonian 3-11 periodic 5-4 prescribed 1-11 split 4-11 steady 1-10. 14-17 in baffles 3-18 in porous media 6-4 solid-fluid 3-16 to 3-20 solid-solid 3-20 help menu 2-17 on-line help 2-2 pro-STAR help 17-7 I I/O window 2-13 IC setup panels 8-23 to 8-37 ideal gas 3-9 law 3-20. 17-4. body 1-9 FORTRAN conventions 14-4 free surface flow 11-1 to 11-5 defined by user subroutines 14-11 density 11-3 differencing schemes 11-2 Version 4. 8-27. 13-7 flame kernel 8-36 flamelet library 8-20 flow axisymmetric 1-12 buoyancy driven 1-13. 17-6 defined by tables 2-24 for liquid films 13-6 for transient analyses 1-18 5 . 8-21. 5-12 solution controls 5-5. 1-20. 8-29. A-4 G gas ideal 3-9 law. 5-4 pressure boundaries 4-14 under-relaxation 3-21 unstable 3-21 cavitating. 11-4 steady-state 11-1 surface tension 11-2 temperature calculation 11-3 free-stream boundary. 5-13. 3-20. 8-15.02 initialisation 11-3 pseudo-transient approach 5-1 solution algorithms 1-13. D-2 force. freestream function keys 16-9 to 16-11. 8-4 ignition 8-10. 1-15 to 1-17 analysis controls 5-1 to 5-4 output controls 5-2 solution controls 5-1 subsonic 3-9 supersonic 1-11. See boundary conditions.Index transient 5-5. 17-7 compressing 5-14 vertex 17-3 view factors 7-3. 4-13 physical 1-9 interface sliding 12-19 solid-fluid 3-18 radiative 7-5 invert set selection option 2-21. 1-14. 13-7 gravitational effect 3-21 initial conditions 13-6 multi-component 13-6 results 13-6 velocity 13-7 with Largrangian multi-phase flow 13-5 lists 6 . inlet inner iterations. near walls 1-7 mean dimension of 1-14 moving 5-14. 12-18 parameters 12-10 post-processing 12-29 pre-processing 12-28 restoration to original state 12-29 with radiation 7-3. injection inlet. See fluid. 8-10 flow rate defined by tables 2-26 defined by user subroutines 14-10 flux 3-22 in excluded cells 12-28 transfer coefficient 14-17 droplet 14-13 in porous media 6-4 material number 3-2. 4-3 iterations inner 1-13 number of 15-1 outer 1-13. 7-5 polyhedral at boundaries attachment 4-39 free-stream 4-33 pressure 4-14 Riemann 4-37 Version 4. 12-9 to 12-13 defined by user subroutines 14-16 in porous media 6-5 mesh preview mode 12-13. 4-26 L Lagrangian multi-phase flow atomisation models 9-1 mesh 9-10 model setup 9-1 nozzle models 9-1 static displays steady-state 9-5 transient 9-8 trajectory displays 9-8 user subroutines 9-1 to 9-3. 9-10. 1-17 iterative calculation 1-19 boundaries 4-3 cells 3-4 cyclic sets 4-31 droplet tracks 9-7 tracks 9-7 lists menu 2-16 load steps 5-6 to 5-14. See block set distortion 1-5 to 1-6 problems caused by 1-16 distribution.Index initialisation procedure in Lagrangian flow using user coding 14-13 in moving meshes 14-17 steady-state run 4-42 transient run 4-42 injection groups 9-2 injection. 3-7 properties 3-1 maximum plot screen 2-32 memory requirements of pro-STAR 17-13 menus 2-16 to 2-17 mesh adaptive refinement 5-17 to 5-19 at non-reflective boundaries 4-18 block. inner input/output window 2-13 instability numerical 1-10. 14-18 definition 5-8 identifying number 5-11 in multi-component mixing 13-3 M macros 16-6 to 16-9 creating 16-7 menus 16-8 modifying 16-7 mass conservation 8-3. See iterations. characteristic 15-2 lift coefficient 14-19 lighting material 3-2 liquid films 13-5 to 13-7 boundary conditions 13-6 boundary regions 13-5 evaporation/condensation 13-6 film stripping 13-5. 14-12 with liquid films 13-5 See also droplet length. See boundary conditions.02 K Kirchoff’s law 4-20. buoyancy driven NavCenter 2-38 near-wall Version 4. multi-component 13-1 mixture fluid 13-1 fraction 8-2. 3-14 mesh distribution 1-7 region 3-13 neutral plot file 2-31.Index stagnation 4-15 supersonic inlet 4-10 transient wave transmissive 4-35 walls 4-22 refinement 5-15 to 5-17 rotating. 5-13 boundary behaviour 5-3 cell behaviour 5-3 field data 5-12 field variables 2-7. coal particles patch number 4-4 radiation 7-2 to 7-7 surface 7-7 7 N natural convection. See flow. See flow. outlet output controls 5-2. 5-12 P panels 16-2 to 16-6 creating 16-2 environment 16-7 files 16-5 manipulating 16-6 menus within 16-3 modifying 16-2 panels menu 2-17 define macros 16-7 define panel 16-2 parallel processing 2-5 for sliding mesh 12-22 run options F-3 to F-7 user subroutines 14-22. 3-12. 5-3. See rotating reference frames 12-1 sliding 12-18 to 12-22 defined by user subroutines 14-16 mesh preview mode 12-22 parallel processing 12-22 regular interface 12-18 to 12-22 without shearing 12-21 tetrahedral. 8-10. E-1 with cell layer removal/addition 12-18 with moving mesh 12-13 parameters 2-36 varying during run 17-18 to 17-20 parcels 9-2. outflow outlet. See boundary conditions. 17-4 new set selection option 2-21. outer outflow. See radiation. 9-6 particle radiation. See boundary conditions. 5-13. 3-14. 17-8. 3-13. 17-19 to 17-21 scalars 5-12 multi-component liquid films 13-6 mixing 13-1 setting up models 13-1 multi-phase flow. number of 11-7 numerical discretisation error 1-6 Nusselt number 14-15 O on-line help 2-2 operate utility 13-4 operating mode 2-18 outer iterations. 14-19. 17-18 numerical solution 5-3. 8-16 model checking 1-20 title 2-19 modelling strategy 1-1 modifying cell type 3-3 to 3-4 modules menu 2-16 transient 5-6. 5-5. 5-18 for compressible flow 3-10 dimensionless normal distance 1-7. non-Newtonian no-slip condition 4-19 NOVICE mode A-1 NOx modelling 8-39 defined by user subroutines 14-15 nozzle models 9-1 nuclei. See Lagrangian multi-phase flow and Eulerian multi-phase flow multiple streams 3-5 to 3-9 of fluid mixtures 13-1 cell 3-12. 15-2 to 15-3. at boundaries free-stream 4-33 pressure 4-14 Riemann 4-37 stagnation 4-15 supersonic inlet 4-10 transient wave transmissive 4-35 walls 4-22 visualisation colour setting 3-1 lighting effect 3-1 message passing routines E-1 mixing. 4-3 non-Newtonian flow. 4-3 none set selection option 2-21. 17-4 monitoring engineering data 4-40. 8-3. 3-13 See also y+ values layer (NWL) 1-7. See iterations.02 . See boundary conditions. defined by user subroutines 14-11 solar 7-1 baffle boundary conditions 4-26 discrete ordinates 7-8 in particpating media 7-3 wall boundary conditions 4-20 sub-domains 7-8 surface exchanges 7-1 transparent solids 7-3 to 7-8 user subroutines 7-6 with STAR-HPC 7-6 Rayleigh model 11-7 reactant 8-2 leading 8-2.02 Q quitting pro-STAR 2-21 8 . 6-5 media in Eulerian multi-phase flow 10-2 in moving mesh 12-13 in multi-component mixing 13-2 user subroutines 14-8 pressure drops 6-5 region modelling 6-1 to 6-5 post menu 2-17 get droplet data 9-3 post register 13-4 post-processor 2-1 power law of viscosity 3-11 Prandtl number 8-17 defined by user subroutines 14-18 precision. See boundary conditions. pressure saturation 11-7 product 8-2 prolinkl script 17-14 prosize script 17-13 pro-STAR 1-2. 7-2. pressure correction 1-13 to 1-15 drop across porous region 6-5 prescribed. See FASTRAC in coal combustion 8-44 in Eulerian multi-phase flow 10-2 on baffles 4-25 participating media 7-3 patch 7-2 to 7-7 properties. 9-5 maximum plot screen 2-32 plot to file 17-4 standard plot mode 2-31 standard plot screen 2-32 plotting hard copies 17-21 porous baffles 4-23. See boundary conditions. 15-2 analysis methods discrete ordinates 7-3 to 7-5. 7-7 escape boundaries 7-5 FASTRAC. precision pre-processor 2-1 pressure 4-5 boundary. 17-7 quitting 2-21 resizing 17-13 size 2-18 pseudo-transient calculation 5-1 for compressible flow 3-11 R radiation 7-1 to 7-8. 8-30 ECFM-3Z 8-28 to 8-30 compression ignition 8-29 to 8-30 spark ignition 8-28 to 8-29 level set 8-31 to 8-32 saving data 8-32 background material 8-17 complex chemistry models 8-11.Index permeability function 1-10 PISO algorithm 1-13 to 1-15 under-relaxation 17-19 plot menu 2-17 alternate plot mode 2-31 background 2-32 cell display 4-41. 8-43 cpu time 7-6. 8-21 coupled 8-16 eddy break-up reaction 8-13 Landau-Teller reaction 8-12 Lindemann fall-off reaction 8-12 SRI fall-off reaction 8-13 sub-timestep 8-21 three-body reaction 8-12 Troe fall-off reaction 8-12 conventions 8-18 copying 8-17 EGR systems 8-17 heterogeneous 8-1 homogeneous 8-1 in Eulerian multi-phase flow 10-2 Version 4. 4-25. See solver. radiation cell table editor 7-8 coal particles 7-5. 8-18 reaction advanced ICE models 8-22 to 8-39 CFM 8-24 to 8-25 ECFM 8-26 to 8-27. 2-1 customisation 16-1 display D-1 to D-3 executables 17-14 launching 2-3. 7-7 to 7-8 discrete transfer 7-1 to 7-7 at walls 4-20 boundaries. 2-10 layout D-3 to D-5 memory 17-13 on-line help 2-36. defining 8-15 variable 8-16 VOF 11-1. 1-16. 8-14 soot modelling. 1-15 oscillations 1-19. 11-6 initialisation 11-4. 2-11 in parallel 2-5 on other hosts 2-5 S Sauter mean diameter 9-9 saving model 2-42 screen 2-33 sets 2-22 scalar CAV 11-6. 7-4 of wall 4-22 solar 4-21. 15-3. 11-8 in fluid mixtures 13-1 initialisation 4-42 numbering 13-3 printing 13-2 properties. 8-16 models 8-1 NOx formation 8-39 partially premixed 8-1 PPDF scheme 8-3 to 8-11. 2-6. 8-17 defined by user subroutines 14-8. 15-1. distributed 6-1 user subroutines 14-8 resizing pro-STAR 17-13 resource allocation F-6 restart 4-42 aeroacoustic analysis 13-4 after mesh changes 5-15 coal combustion 8-44 data 5-13 files 2-7 flamelet calculations 8-20 Lagrangian multi-phase 9-10 moving mesh 12-13 multiple runs 5-14 Version 4. 2-4. 7-2 thermal 4-20. defined by tables 2-25 running simulations 2-2. See soot modelling source term 14-11 temperature limit 8-21 turning off 8-17 types 8-1 unpremixed/diffusion 8-1 user subroutines 14-15 real constants 5-3 recovery 2-20 re-executing commands 2-20 reference temperature 15-2 reflectivity of baffle 4-26 solar 4-26. defined by tables 2-25 rothalpy. 7-1. 5-10 turbulence models 3-16 view factors 7-5 with INITFI 14-17 restoring sets 2-22 results checking 1-20 RESULTS sub-directory 2-7 resume mode 2-13 rotating reference frames arbitrary interface 12-4 coupling 12-8 defined by user subroutines 14-16 multiple explicit method 12-5 to 12-9 non-reflecting explicit option 12-9 implicit method 12-2 to 12-5 single 12-1 rotation 1-9 rotational speeds. 14-18 screen capture 2-33 high-resolution 2-33 display control 2-18 dump 2-33 size 2-32 storage 2-32 9 . 7-4 regress variable 8-10 relaxation factors 1-15. 15-2 residuals 1-15. 2-7. 8-16 eddy break-up models 8-10 flame-area models 8-10 CFM-ITNFS 8-10 Weller 8-10 Weller 3-equation 8-10 schemes 8-2.02 non-reflective boundaries 4-18 run options F-2 steady-state runs 4-42. 5-6. 11-9 scalar solver 1-19 scattering coefficient 7-4 Schmidt number 6-4. 17-19 for transonic flow 3-10 inner 1-13. 1-19. 8-18 to 8-19 multi-fuel 8-9 single-fuel 8-3 equilibrium models 8-3 with dilutants 8-9 premixed 8-1 rate. 17-19 resistance. defined by user subroutines 14-15 regress variable models 8-10.Index local source model 8-2. 5-4 transient runs 4-43. 10-4. in rotating reference frames 12-5 roughness 14-6 run time controls. 2-7 tolerance 8-16. 7-2 thermal 4-25. 7-1. at inlet 8-20 subset set selection option 2-22. with radiation problems 7-6. 15-2 defined by user subroutines 14-9 in multi-component mixing 13-3 spin index 12-3. A-2 stability numerical 1-5.02 . defined by user subroutines 14-11 turbulence 3-9 defined by user subroutines 14-10 species mass fraction 8-4 defined by user subroutines 14-16 10 in coal combustion 8-44 reacting 8-2 specific heat 8-17. symmetry system commands. See boundary conditions. See mesh. sliding solid regions 15-2 initialisation 4-42 solid-fluid heat transfer 3-8. stagnation STAR 1-2 defaults F-7 run options F-1 to F-12 running 2-4. 17-19 switches 5-3 for ‘prostar’ system command 2-4 for ‘star’ system command 2-5. 8-19. 12-4 to 12-8 velocity 12-1. 5-16 procedure 15-1 solver conjugate gradient 1-19 precision 1-18 for Eulerian multi-phase flow 10-3 for liquid films 13-6 tolerances 1-14. 7-5 solid-solid heat-transfer 3-20 solution algorithms 1-13 to 1-18 for buoyancy driven flow 3-21 for cavitating flows 11-9 for use with DES turbulence models 3-15 for use with LES turbulence models 3-15 in free surface flows 11-4 controls 5-1.Index set active cell type 3-3 sets restoring 2-22 saving 2-22 set-up files 16-1 shock wave 4-32 short cut keys. 1-15. 12-6 parameters 12-1. entering in pro-STAR 2-18 T tables dependent variables 2-27 editor 2-26 to 2-31 graphs of 2-29 hints 2-31 independent variables 2-27 title 2-27 usage in boundary conditions 2-24. F-1 to F-12 STAR-GUIde 2-38 check everything panel 4-6 favourites 2-40 STAR-HPC. 1-16 to 1-18 single precision mode 1-18 sliding mesh. F-1 to F-12 symmetry plane. 1-16. 4-3 surface tension 11-2 coefficient 14-12 surface set selection option 2-22 sweep limits 1-14. See boundary conditions. 7-7 STAR-Launch utility 2-8 to 2-12 STAR-NET F-8 to F-12 STAR-View 17-23 StarWatch utility 17-15 to 17-21 states 17-6 steady-state calculation 1-15 to 1-17 stoichiometry. 15-2 sweeps 1-13. 1-16. 1-15. checking 8-16 strain rate. speed of 14-12 source aeroacoustic 13-4 defined by tables 2-24 enthalpy 3-9 defined by user subroutines 14-10 in cavitating flows 11-9 in Eulerian multi-phase flow 10-3 in free surface flows 11-4 mass 3-8 defined by user subroutines 14-10 momentum 3-8 defined by user subroutines 14-10 scalar. See function keys short input history 2-15 SIMPLE algorithm 1-13. 8-29. 5-5. 3-16 to 3-20. 15-2 hints 3-19 in free surface flows 11-2 radiative 7-3. 8-40 sound. 12-4 spline set 2-21. 2-11 switches 2-5. 5-9 domain 1-2 mapping 5-15. 15-2 soot modelling 8-39 to 8-41 flamelet library model 8-39 PSDF moments model 8-26. 2-5. 1-10 dependence on time step 5-9 stagnation boundary. 4-7 baffles 4-27 free-stream 4-33 Version 4. 3-13 to 3-14 wall functions 3-12. 12-4. 7-1. 1-15. See flow. 7-1. 7-4 turbomachinery. boundaries for 4-16 turbulence 3-12 to 3-16 changing model 3-16 DES models 3-15 hybrid wall functions 3-12. See radiation time characteristic 1-14 cpu 2-18. 15-2 Reynolds stress models 3-15 conditions at boundary free-stream 4-33 inlet 4-10 Riemann 4-37 stagnation 4-15 transient wave transmissive 4-35 two-layer models 1-8. 5-6. 7-2 thermal 4-20. 3-20 density 1-15 for compressible flow 3-10. 3-13 non-equilibrium 3-13 tutorials 2-37 two-dimensional flow. 12-9 initialisation 4-42 length scale 14-9 LES models 3-15 low Reynolds number models 3-12. 3-11 completion 2-7 full 5-6 to 5-14 single 5-4 to 5-6 transient wave boundary. 7-4 of wall 4-22 solar 4-21. 15-3 reducing 1-16 elapsed 2-7 elapsed computational 15-3 ignition delay 8-37 scale 5-9 heat/mass transfer 8-44 step 1-10. axisymmetric two-phase flow. temporal thermal resistance 3-17 runaway 1-10 thermal radiation. 1-18 defined by tables 2-25 number of 15-1 specification 5-11 variable 14-18 varying during run 17-18 See also Courant number tools menu 2-16 cell tool 3-3 check tool 3-5 colour tool 17-22 convert 17-8 Version 4. 3-12. 3-14 in aeroacoustic analysis 13-4 in ECFM combustion models 8-30 in porous media 6-4 in rotating reference frames 12-2. 3-14 models 3-12. 3-11 for moving mesh 12-13 for steady-state calculations with PISO 1-15 for steady-state calculations with SIMPLE 1-16 for transient calculations with SIMPLE 1-17 in buoyancy driven flow 3-21 in cell layer removal/addition 12-18 11 . See Lagrangian multi-phase flow and Eulerian multi-phase flow U under-relaxation 1-10. See discretisation. 7-2 thermal 4-25. axisymmetric. transient wave transmissive transient waves 4-34 transmissivity at solid-fluid interface 7-5 of baffle 4-26 solar 4-26.02 users tool 2-35 transient calculation 1-13 to 1-15. 7-4 reference 15-2 in restart runs 5-17 stagnation 3-11 under-relaxation 17-19 temporal discretisation.Index inlet 4-10 non-reflective 4-19 outlet 4-12 pressure 4-14 Riemann 4-37 stagnation 4-16 transient wave transmissive 4-35 walls 4-22 initial conditions 2-24 injectors and sprays 2-26 rotational speeds 2-25 run-time controls 2-25 source terms 2-24 tcl/tk interpreter 2-35 temperature at free-stream boundary 4-33 at Riemann boundary 4-37 at transient wave transmissive boundary 4-35 defined by user subroutines 14-7 devolatilisation 8-43 distribution 3-17 functional dependence 14-7 in cavitating flows 11-8 in free surface flows 11-3 limit on reaction 8-21 radiation 7-2. 5-9 adjusting 1-14. See boundary conditions. 7-5 viscosity defined by user subroutines 14-9 in chemical reaction problems 8-17 oscillations 1-15 power law 3-11 turbulent 14-9 under-relaxation 1-15 viscous sublayer 3-13 volume of fluid (VOF) model 11-1 volume. 14-16 for porous media 6-4. dimensionless normal distance Z Zeldovich mechanism 8-39 Version 4. 14-12 for moving mesh 12-9. wall wave compression 4-32 expansion 4-32 shock 4-32 transient 4-34 V vaporization rate 14-12 vapour in cavitating flows 11-7 variables 2-36 vector solver 1-19 velocity angular. 15-2 activating 14-2 checking 1-20 defining material properties 14-6 to 14-9 editing 14-4. 4-3 unsteady calculation. 12-9 data 17-3. 17-10 for boundaries 4-7. of droplet 9-10 W wall 1-3 boundary layer 1-6 data 5-3 functions 1-7. 2-36. 14-1 to 14-22. 3-15 See also near-wall. 14-8 for rotating reference frames 12-1. 14-5 for chemical reactions 14-15 for Eulerian multi-phase flow 14-14 for heat and mass fluxes 14-6 for heat and mass transfer coefficients 13-3. 3-13.Index in chemical reaction problems 8-16 in Eulerian multi-phase flow 10-4 in multi-component mixing 13-3 pressure 1-16 pressure correction 1-14 varying 17-19 velocity 1-16 viscosity 1-15 units 2-36. A-2 view factor 7-3. 12-4. 14-10 in droplet injection 9-1 to 9-3 in parallel processing runs 14-22. C-1 unselect set selection option 2-21. See transient calculation user interface 2-35 user subroutines 2-4. 14-16 for solar radiation 7-6 for turbulence 14-9. See angular velocity at stagnation boundaries 4-15 boundary values 4-27 characteristic 1-14 in porous media 6-5 injection 3-22 defined by user subroutines 14-10 of baffles 4-27 of liquid films 13-7 12 Y y+ values 1-21. 3-12 hybrid 1-8 heat flux 5-5 defined by user subroutines 14-17 moving 4-19 no-slip 4-19 patch 7-2 radiation 4-20 to 4-22 transmissive external 7-5 transparent 4-21 velocity 4-22 See also boundary conditions. 17-9 maximum number of 2-18 set 2-21. 2-18.02 . E-1 users tool 2-35 utility menu 2-17 calculate volume 3-22 capture screen 2-33 count 4-2 function keys 16-10 save screen as 2-33 solution mapping 5-16 user subroutines 14-2 write STAR-CD scene file 17-23 of walls 4-22 vertex coordinate in moving mesh 5-14. 12-8. 14-17 for Lagrangian multi-phase flow 9-10. 12-21. 3-19 CCLIST 17-6 CCROSS 3-4 CDELETE 12-29 CDISPLAY 4-41. 12-17. 12-15. 9-8 DTIME 9-5. 12-17. 12-29 to 12-30 EHTRANSFER 14-15 EICOND 14-17 ETURB 14-14 EVCHECK 12-30 EVCND 12-26 EVCOMPRESS 12-12. 12-17. 12-29 CTABLE 3-2. 12-29 EATTACH 12-20. 12-27 EVPARM 12-10 EVPREP 12-12. 12-28 EDLIST 12-26 EDRAG 14-14 EECELL 12-28 EFLUID 12-26 EGRID 12-11. 16-5 COKE 14-18 CONDUCTIVITY 14-6 COUNT 4-2 CPLOT 12-12 CPOST 5-11 CPRANGE 5-11 CPRINT 5-11 CPSET 2-24 CREFINE 16-4 CRMODEL 14-16 CSET 2-24. 7-2 BGENERATE 4-2 BLIST 4-4 BLKSET 2-24 BMODIFY 4-2. 12-27 EVLOAD 12-29 to 12-30 EVOFFSET 12-12. 12-20. 12-20. 4-3. 9-5 CDSAVE 17-3 CDSCALAR 13-3 CDTRANS 5-11. 16-5 CURSORMODE 2-19 CYCLIC 4-29 CYCOMPRESS 4-31 CYDELETE 4-31 CYGENERATE 4-29 CYLIST 4-31 Version 4. 12-16. 7-6 BSET 2-24. 3-4 CTDELETE 3-2 CTLIST 3-2 CTMODIFY 3-2 CTNAME 3-2 CTYPE 3-4. 7-2. 12-25 EVFLAG 12-30 EVGET 12-12.INDEX OF COMMANDS INDEX OF COMMANDS This User Guide does not contain comprehensive information on all commands used in pro-STAR. 12-20 EVDELETE 12-12. 4-4 BSHELL 4-2. 12-26 EVEXECUTE 12-29 to 12-30 EVFILE 12-11. 12-27 ECHOINPUT 2-19 ECLIST 12-16 ECONDITIONAL 12-26 EDATA 5-3 EDCELL 12-16 EDCOMPRESS 12-26 EDDELETE 12-26 EDDIR 12-16 EDETACH 12-21. 12-26 EVLIST 12-12. 12-24 CTCOMPRESS 3-2. 12-17. 4-4. 17-4 CFIND 3-4 CJOIN 5-19 CLOSE 17-10 CLRMODE 2-32 CLRTABLE 17-22 CMODIFY 3-5. 9-7 B BATCH 2-18 BCROSS 4-2. 7-2 C CASENAME 17-1 CAVERAGE 12-29 CAVITATION 14-11 CAVNUCLEI 14-11 CAVPROPERTY 14-12 CBEXTRUDE 3-18. 12-20. 7-6 BDEFINE 4-2. 7-2 BDELETE 4-4 BDISPLAY 4-41. 12-17. 12-21. 12-17. 12-27 EVSAVE 12-11 EVSLIDE 14-16 1 . 12-27 EVREAD 12-12.02 E EACELL 12-16 EACOMPRESS 12-20 EADELETE 12-20 EAGENERATE 12-20 EALIST 12-20 EAMATCH 12-19. 12-13. 12-16. 12-21. 12-17. The Meshing and Post-Processing Guides and on-line STAR GUIde Help should also be consulted A ABBREVIATE 16-1 ABORT A-1 CZONE 3-4 D DAGE 9-7. 9-8 DCOLLISION 14-12 DELTIME 14-18 DENSITY 14-8 DIFFUSIVITY 14-8 DLIST 9-8 DRAVERAGE 14-12 DRCMPONENT 14-13 DRHEAT 14-13 DRMASS 14-13 DRMOMENTUM 14-13 DRPROPERTIES 14-13 DRUSER 14-13 DRWALL 14-13 DSCHEME 14-19 DSET 2-24. 9-6. 12-20. 12-27. 12-20. 14-6 RECALL 2-20 RECOVER 2-20. 17-2 SC 13-3 SCCONTROL 13-3 SCDUMP 2-33 SCENE 17-23 SCPOROUS 14-8 SCPROPERTIES 13-3. 14-5. 17-3. 12-16. 17-12 IGNMODEL 14-15 INITIAL 14-17 ITER 5-14 Q QUIT 2-21. 13-2 SETADD 2-23 SETDELETE 2-22 Version 4. 17-7 PROMPT 16-7 PRTEMP 3-18 PTCONV 17-8 PTPRINT 9-7.Index of Commands EVSTEP 12-11. 12-17. 9-8 PTREAD 9-7 G GEOMWRITE 12-12. 17-4. 12-10. 12-27. 12-17. 2-42 K KNOCK 14-15 R RADPROPERTIES 14-11 RCONSTANT 12-18 RDEFINE 12-19. 14-17 N NFILE 17-4 NOX 14-15 2 . 12-27 EVWRITE 12-12. 12-9. 12-25 MVGRID 5-11. 12-20. 17-5 GETCELL 12-12 GETD 8-36 H HCOEF 14-17 HISTORY 2-19 to 2-20 HRSDUMP 2-33 I IFILE 13-3. 2-42 REPEAT 16-10 REPLOT 16-3 RESET 2-32 RESUME 2-42. 17-2. 17-10 REWIND 17-10 RGENERATE 4-7 RRATE 14-15 RSOURCE 14-10 RSTATUS 8-17 L LFQSOR 14-14 LFSTRIP 14-14 LQFBC 14-14 LQFINITIAL 14-14 LQFPROPERTY 14-14 LSCOMPRESS 5-11 LSDELETE 5-11 LSGET 5-11 LSLIST 5-10 LSRANGE 5-11 LSSAVE 5-10 LSTEP 5-10. 12-27. 12-16 EVUNDELETE 12-12. 12-25 PRFIELD 14-19 PROBLEMWRITE 12-12. 12-20. 12-20. 12-17. 17-10 P PAGE 2-19 PATCH 7-7 PLATTACH 12-30 PLTBACK 2-33 PLTYPE 12-12 PMATERIAL 12-25 POPTION 12-12 POREFF 14-8 POROSITY 14-8 PORTURBULENCE 14-8 PRESSURE 12-18. 14-18 LVISCOSITY 14-9 S SAFETY 2-20 SAVE 2-42. 16-6 OPEN 16-10 F FSTAT 2-23. 14-16. 17-10. 14-18 SCRDELETE 2-33 SCRIN 2-32 SCROUT 2-32 SCSOURCE 14-11 SCTRANS 5-11. 12-23. 12-17. 14-16. 12-21.02 M MACRO 16-9 MEMORY 17-14 MFRAME 14-16 MLIST 3-9 MMPISTON 12-13 MONITOR 12-18. 12-27 EXPERT A-1 O OFILE 17-10 OPANEL 16-1. 5-10. 17-4 TRLOAD 12-12 TSCALE 2-33 TSMAP 5-16 TURBULENCE 14-9 U USER 2-18 USUBROUTINE 14-3 V VAPORIZATION 14-12 VFILL 12-11 VLIST 16-5 VMOD 12-11 VMODIFY 2-24 VOLUME 3-22 VSET 2-24. 14-18 TITLE 2-19 TLMODEL 14-9 TPRINT 2-18 TRFILE 2-42. 12-15. 17-21 TEXT 2-18 TIME 12-10. 5-16 SMCONV 17-8 SOLAR 14-11 SPECIFICHEAT 14-7. 17-4.02 3 . 2-30 TBLIST 2-30 TBMODIFY 2-30 TBREAD 2-30 TBSCAN 2-31 TBWRITE 2-28 TDSCHEME 5-11 TERMINAL 2-31. 12-11 VSMOOTH 12-30 W WHOLE 2-32 WIPEOUT 17-14 WPOST 5-11 WPRINT 5-11 Version 4. 12-25 STENSION 14-12 STORE 12-12 SUCCEED 2-20 SYSTEM 2-18 T TBCLEAR 2-28 TBDEFINE 2-28 TBGRAPH 2-28. 14-9 SPIN 14-16 SPLSET 2-24 STATUS 2-42.Index of Commands SETENV 16-6 SETFEATURE 16-1 SETREAD 2-23 SETWRITE 2-22 SIZE 2-18 SMAP 5-15.