Computer Aided Thermal Computer Aided Thermal Fluid AnalysisFluid Analysis

Lecture 2Lecture 2

Dr. Ming-Jyh ChernDr. Ming-Jyh Chern

ME NTUSTME NTUST

Road Map for TodayRoad Map for Today

• How to initialize STAR-CD?How to initialize STAR-CD?

• Four major modeling processes.Four major modeling processes.

• Usage of SETUsage of SET

• Generation of VerticesGeneration of Vertices

prostar - Exceed prostar - Exceed

• STAR-CD was coded under an X-STAR-CD was coded under an X-window environment. window environment.

• To run STAR-CD in MS Window, a To run STAR-CD in MS Window, a program to transform images given program to transform images given by STAR-CD is necessary.by STAR-CD is necessary.

• Exceed is able to reach this goal. Exceed is able to reach this goal. You need to run exceed before the You need to run exceed before the usage of STAR-CD. usage of STAR-CD.

STAR-CD Launcher STAR-CD Launcher

prostar - Exceed prostar - Exceed

prostar prostar

Command WindowCommand Window

STAR-GUIDE STAR-GUIDE

Quit from STAR-CD Quit from STAR-CD

Four Major Modeling ProcessFour Major Modeling Process

• Phase 1 – Working out a modeling Phase 1 – Working out a modeling strategystrategy

• Phase 2 – Preprocessing - Setting up Phase 2 – Preprocessing - Setting up the flow model using the flow model using PROSTARPROSTAR

• Phase 3 – Solver - Performing the flow Phase 3 – Solver - Performing the flow analysis using analysis using STARSTAR

• Phase 4 – Post-processing the results Phase 4 – Post-processing the results using using PROSTARPROSTAR

Phase 1 – Working out a Phase 1 – Working out a Modeling StrategyModeling Strategy

• Planning the computational meshPlanning the computational mesh

• Looking up numerical values for Looking up numerical values for appropriate physical parametersappropriate physical parameters

• Choosing the most suitable modeling Choosing the most suitable modeling option from what is available. option from what is available.

Phase 2 – Setting Up the Flow Phase 2 – Setting Up the Flow Model Using ProstarModel Using Prostar• Creating a computational mesh to represent the flow Creating a computational mesh to represent the flow

domain.domain.• Specifying the thermophysical properties of the fluids Specifying the thermophysical properties of the fluids

and/or solids.and/or solids.• Setting the solution parameters and output data formSetting the solution parameters and output data form

ats.ats.• Specifying the location and definition of boundaries aSpecifying the location and definition of boundaries a

nd time increment.nd time increment. • Writing appropriate data files.Writing appropriate data files.

Phase 3 – Performing the Flow Phase 3 – Performing the Flow Analysis Using ProstarAnalysis Using Prostar• Reading input data created by Prostar aReading input data created by Prostar a

nd, if dealing with a restart run, the resulnd, if dealing with a restart run, the results of a previous run.ts of a previous run.

• Judging the progress of the run by analyJudging the progress of the run by analysing various monitoring data and solutiosing various monitoring data and solution statistics provided by STAR.n statistics provided by STAR.

Phase 4 – Post-processing the Phase 4 – Post-processing the results Using Prostarresults Using Prostar• Display and visualize the obtained Display and visualize the obtained

results.results.

• Plot velocity vector fields.Plot velocity vector fields.

• Plot contours regarding pressure, Plot contours regarding pressure, density and so on.density and so on.

• Plot curves regarding variation of Plot curves regarding variation of flow fields. flow fields.

STAR-CD System StructureSTAR-CD System Structure

Pro-STARPro-STAR

STARSTAR

Files in STAR-CDFiles in STAR-CD

Usage of MouseUsage of Mouse

• Left bottom – RotationLeft bottom – Rotation

• Middle bottom (or Left+Right Middle bottom (or Left+Right bottoms) – Zoombottoms) – Zoom

• Right bottom - MoveRight bottom - Move

Basic Elements Basic Elements

• CellCell• VertexVertex• BoundaryBoundary• BlockBlock• CoupleCouple• SplineSpline• DropletDroplet

Concept of Set Concept of Set

• Every command or action in STAR-CD Every command or action in STAR-CD only affects elements in a set. Before only affects elements in a set. Before you give a command, you’d better syou give a command, you’d better select the elements which you want to elect the elements which you want to modify.modify.

• The range of a set can be checked via The range of a set can be checked via “List” in Prostar. “List” in Prostar.

When set is used? When set is used?

• Plot resultsPlot results

• Establish modelEstablish model

• Check modelCheck model

• Post-processingPost-processing

Common sets Common sets

• cset: Cell setcset: Cell set• vset: Vertex setvset: Vertex set• bset: Boundary setbset: Boundary set• splset: Spline setsplset: Spline set• Blkset: Block setBlkset: Block set

Coordinates Coordinates

• Global coordinateGlobal coordinate

• Local coordinateLocal coordinate

• Cartesian coordinateCartesian coordinate

• Cylindrical coordinateCylindrical coordinate

• Spherical coordinateSpherical coordinate

Coordinates Coordinates

• Change or view setting of coordinate sChange or view setting of coordinate system from STAR GUIde.ystem from STAR GUIde.

• Create and Import Geometry->Create Create and Import Geometry->Create Geometric Entities-> find vertices in thGeometric Entities-> find vertices in the yellow part-> click the icon near “Ce yellow part-> click the icon near “Current Coordinate System”urrent Coordinate System”

Coordinates Coordinates

Current system

Command For Vertex Command For Vertex Generation Generation

• Before you generate a vertex, you’d Before you generate a vertex, you’d better to check which coordinate you better to check which coordinate you use.use.

• v,1,0,0,5v,1,0,0,5• v,2 ,10,0,0v,2 ,10,0,0• vset,allvset,all• vplotvplot

Alternative Way to Generate Alternative Way to Generate a Vertexa Vertex

Vertex ListVertex List

• Find vertex list from the item “VerticesFind vertex list from the item “Vertices” of “Lists” in Prostar” of “Lists” in Prostar

Vertex ToolVertex Tool• Find vertex tool from the item “Vertex TFind vertex tool from the item “Vertex T

ool” of “Tools” in Prostarool” of “Tools” in Prostar

Vertex ToolVertex Tool