introduction 9.04

Introduction

Welcome to the STAR-CCM+ introductory tutorial. In this tutorial, youexplore the important concepts and workflow. Complete this tutorialbefore attempting any others.

Throughout this tutorial, links to other sections of the onlinedocumentation explore important concepts. For example, for a clearerunderstanding of the changes to typeface in the tutorials, refer to thetypographic conventions.

This tutorial is useful in addition to STAR-CCM+ training. For morehelp, contact your local CD-adapco office. A list of contacts is found at: http://www.cd-adapco.com/about/locations.html.

The case is a transonic flow over an idealized symmetrical blunt body ina wind tunnel.

The tutorial workflow includes:

• Importing the geometry files.

• Generating a polyhedral mesh.

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• Setting boundary names and types.

• Defining the models in the continua and applying them to theregions.

• Defining the region conditions, values, and boundary conditions.

• Running the simulation.

• Post-processing the results.

These steps follow the general workflow for STAR-CCM+.

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Starting a STAR-CCM+ SimulationStart the simulation and familiarize yourself with the STAR-CCM+ userinterface.

1. Launch STAR-CCM+ using the appropriate instructions for youroperating system.

After a brief display of the splash screen, the STAR-CCM+ clientworkspace opens without loading an existing simulation or creatinga simulation. This interface to the STAR-CCM+ software is a self-contained graphical user interface (GUI) with panes andsubwindows. Some of the GUI terminology is shown in thefollowing screenshot.

The menu bar provides access to application-wide actions, withsome of the more important actions being duplicated in the toolbar.

2. Let the mouse hover over any of the buttons in the toolbar.

A short description of what that button does appears in a tooltip. Inthis case, the tool tip shows the name of the bar.

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Creating a SimulationCreating a simulation is the first step in a new STAR-CCM+ analysis.

STAR-CCM+ is a client-server application with the client (user interfaceor batch interpreter) running in one process, and the server (the solver)running in another process. Start a server process on the same machineas the client:

1. Start a simulation by selecting File > New Simulation from themenu bar.

The Create a New Simulation dialog appears.

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2. In the Create a New Simulation dialog, click OK.

A new window containing a simulation object tree is created in theExplorer pane, with the name Star 1. The initial folder nodes for thissimulation are shown in the following screenshot. Other nodes areadded to the object tree as you progress further.

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As the new simulation is created, a window that is named Outputappears in the lower-right portion of the STAR-CCM+ workspace.The Output window describes the progress of actions in thesimulation.

Working with ObjectsMuch of your interaction with the simulation is through the objects inthe simulation tree that was added to the Explorer pane.

Familiarize yourself with the objects in the simulation tree:

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The tree represents all the objects in the simulation. Nodes are added inlater sections when a geometry is imported and models are defined inthe continuum. Most of your interaction with the simulation is byselecting nodes in the tree and:

• Right-clicking to expose an action menu.

• Using keys to, for example, copy and delete objects.

• Dragging objects to other tree nodes or onto visualization displays.

The handle next to a node indicates that subnodes exist below that one.To open a node and show the subnodes, click the handle. To close it, dothe same for an open node.

Most objects in the tree have one or more properties that define theobject. Access to the properties is through the table.


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To modify the properties of an object, click its node once to select it. Editmost types of properties in the value cell. Otherwise, when settingvalues of complex properties, click the Property Customizer button tothe right of the value. A property-specific dialog opens.


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Saving and Naming a SimulationThe simulation file (.sim) contains STAR-CCM+ analysis setup, runtime,and results information.Here, you save the simulation to disk.

To save the simulation:

1. Select File > Save As.2. Navigate to the directory where you want to locate the file.

3. In the Save dialog, type bluntBody.sim into the File Name text box

and click Save.The title of the simulation window in the Explorer pane updates toreflect the new name.

It is useful to save work in progress periodically. This tutorial includesreminders to save the simulation at the end of each section. If youwould like to return to a stage of the tutorial at a later stage, save it witha unique name.

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Importing the GeometrySTAR-CCM+ provides tools to generate the geometry, but for thistutorial you start from a pre-generated Parasolid file of the design.

Before solving this case, you can recognize that the flow is likely to besymmetrical in two planes around the body. Hence, only a quarter ofthe geometry is modeled. This symmetry condition reducescomputational costs and solution time without losing information oraccuracy.

The first step in this tutorial is to import the geometry:

1. Select File > Import > Import Surface Mesh from the menu bar.2. In the Open dialog, navigate to the doc/startutorialsdata/

introduction/data subdirectory of your STAR-CCM+ installationdirectory and select file bluntBody.x_t.

3. To start the import, click Open.

The Import Surface Options dialog appears.4. Select Create new Part from the Import Mode box.

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5. Click OK to import the geometry.

STAR-CCM+ provides feedback on the import process in the Outputwindow. A new geometry scene is created in the Graphics windowand shows the imported geometry.

6. In the simulation tree, expand the Geometry > Parts node to see thenew bluntBody part.


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The imported geometry represents the fluid volume around thebody in the wind tunnel.

7. Save the simulation by clicking Save.


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Visualizing the Imported GeometryThe Geometry Scene 1 display is already present in the Graphics window.Initially, solid, colored surfaces show the surfaces of the geometry.

View the imported geometry in the Graphics window.

A new geometry scene contains:

• A part displayer, Geometry 1, which contains all faces in thegeometry part and is preset to display a shaded surface.

• A second part displayer, Outline, which also contains all faces in thegeometry part and is preset to display the mesh outline.

Panning, Zooming, and Rotating the ViewFamiliarize yourself with the options to change the view of thegeometry.

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In the Graphics window, all three mouse buttons have drag operationsthat change the view of the geometry:

• To rotate about the selected point, hold down the left mouse buttonand drag.

• To zoom in or out, hold down the middle mouse button and drag.• To translate or pan, hold down the right mouse button and drag.• To rotate around an axis perpendicular to the screen, press the

<Ctrl> key and hold down the left mouse button while dragging.

There are also several “hot” keys that rotate the view:

• To align with the X-Y plane, press the <T> key.• To align with the Y-Z plane, press the <F> key.• To align with the Z-X plane, press the <S> key.• To fit the view within the Graphics window, press the <R> key.

1. Adjust the view as shown in the following screenshot.

2. Save the simulation.

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Defining Boundary SurfacesSpecify the boundary type for each surface.

The following illustration gives an overview of how you set up thisproblem.

Index Description

1 Stagnation Boundary2 Wall3 Symmetry Planes4 Pressure Boundary5 Slip Walls

Split the surfaces that form specific boundaries:

1. Open the Geometry > Parts > bluntBody > Surfaces > Faces node.2. Right-click the Faces node and from the pop-up menu, select Split

by Patch.

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The Split Part Surface by Patch dialog appears.

3. In Geometry Scene 1, select the face in the low X direction, rotatingthe geometry as necessary.


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4. Type Inlet in the Part Surface Name field.


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5. Click Create.

The face is removed from the scene and the new surface appearswithin the surfaces manager node belonging to the parent part.

6. Repeat the previous steps for the following surfaces:

Location Corresponding part surface patchnumber

Name

High X face 3 Pressure

Low Z face 4 Symmetry_plane1

Low Y face 6 Symmetry_plane2

The outside walls of the region can be defined as a single boundary bycombining two faces into one part surface using the multi-selectfunctionality.

7. Hold down the <Ctrl> key and click both the High Y and High Zfaces.

8. Type Slip_wall in the Part Surface Name.


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9. Click Create.

The remaining patches remain as part of the default surface.

10. Click Close.11. Save the simulation.

Renaming the Surface and PartRenaming nodes is a common operation in STAR-CCM+. There are twoways a node can be renamed.

Rename the Faces node and the bluntBody part:

1. Select the Geometry > Parts > bluntBody node.2. Press <F2>.3. Rename the part subdomain-1.

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4. Press <Enter> or click another node to accept.

To rename the Faces part surface, the previous method can be used. Usethe alternative right-click menu option:

5. Right-click the Geometry > Parts > subdomain-1 > Surfaces > Facesnode and select Rename....

6. In the Rename dialog, enter Inner_wall and click OK.


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The parts are ready to be converted to a region and boundaries.7. Save the simulation.


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Assigning Parts to RegionsGeometry parts are used to prepare the spatial representation of themodel. The computational model to which physics can be applied isdefined in terms of regions, boundaries, and interfaces.

Create a region and associated boundaries from the geometry part andits surfaces:

1. Right-click Geometry > Parts > subdomain-1 and select AssignParts to Regions....

The Assign Parts to Regions dialog appears.

2. Select Create a Region for Each Part.3. Select Create a Boundary for Each Part Surface.

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4. Click Apply.5. Close the dialog.

The portion of the object tree below the Regions node appears asshown below. All of the surfaces appear as individual boundarieswithin the region.


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Setting Boundary TypesHaving previously given the boundaries sensible names, you can set theboundary types.

Specify the appropriate boundary types:

1. Select the Symmetry_plane1 node and set Type to Symmetry Plane.

The boundary node icon changes to reflect the new type.2. Using the same technique, change Symmetry_plane2 to Symmetry

Plane.

For compressible flows, the most appropriate inflow and outflow typesare stagnation inlet and pressure outlet.

3. Change the type of the Inlet boundary to Stagnation Inlet and thetype of the Pressure boundary to Pressure Outlet.The Slip_wall and Inner_wall boundaries retain the default Walltype. Slip walls are boundary conditions and are set up later.


Selecting PartsSTAR-CCM+ highlights selected parts in the visualization window.

To highlight parts:

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1. Click a part in the Geometry Scene 1 display, for example the High Xface.

The object becomes highlighted and a label appears with the nameof the object selected.

In the bluntBody object tree, the node that corresponds to this objectis also highlighted.

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Conversely, if a boundary node is selected in the bluntBody tree, thesurface corresponding to that boundary is highlighted in theGraphics window.

Adding and Removing Parts from a SceneUse the part selector dialog to add and remove parts from a scene.

To add and remove some parts:

1. Open the Scenes > Geometry Scene 1 > Displayers > Geometry 1 >Parts node and click the ellipsis (Custom Editor) for the Parts value.

The Parts dialog appears.

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2. Click (Column Selection) to clear the current selections.3. Expand Regions > subdomain-1 > Boundaries.4. Select Inner_wall.


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5. Click OK.

This selection removes the solid-colored boundaries representing thewind tunnel from the scene, leaving the outlines and the blunt body.

Add those parts back to the scene using a drag-and-drop method:

6. Open the Regions > subdomain-1 > Boundaries node.7. To extend your selection, hold down the <Ctrl> key and select all

the boundary nodes except Inner_wall.8. Release the <Ctrl> key but continue to keep the left mouse button

pressed.9. Drag the nodes onto the display and release the left mouse button.

A pop-up menu appears.

Use this menu to choose which of the part displayers in the scenereceive the parts that you have dragged across.


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10. Select Add to Geometry 1.

The parts are restored to the scene.



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Generating the MeshSeveral steps are involved in defining and generating a volume mesh.

To generate the mesh:

1. Create a mesh continuum.

2. Choose appropriate meshing models.

3. Specify initial global settings.

4. Modify the boundary-specific settings.

Creating the Mesh ContinuumThe mesh continuum is used to specify the required meshing models.

To create the mesh continuum:

1. Right-click Continua.2. Select New > Mesh Continuum.

A new node, Mesh 1, is added to the simulation tree.

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Choosing Meshing ModelsThe meshing continuum has a Models node which you can nowpopulate.

To choose the meshing models:

1. Right-click the Mesh 1 node and choose Select Meshing Models....

In the Mesh 1 Model Selection dialog:

2. Select Surface Remesher from the Surface Mesh group box.3. Select Polyhedral Mesher and Prism Layer Mesher from the

Optional Models group box.

The Enabled Models section appears as shown below.

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4. Click Close.5. Expand the Models and Reference Values managers.

The simulation tree appears as shown below.

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Specifying the Mesh SettingsGenerating a mesh often requires several iterations to achieve thedesired density and distribution of cells. In this tutorial, you generate avolume mesh, add some simple refinement, and regenerate.

To specify the mesh settings:

1. Select the Continua > Mesh 1 > Reference Values > Base Size nodeand set Value to 0.01 m.

With this base size, approximately 8 cells are created across thewidth of the region.

2. Select Continua > Mesh 1 > Reference Values > Number of Prism

Layers and set Numbers of Prism Layers to 5.

Generating the Volume MeshNow that you have specified the appropriate settings, you can generatethe volume mesh.

1.Click (Generate Volume Mesh) in the toolbar or select GenerateVolume Mesh in the Mesh menu.

The run and progress of the meshers are displayed in the Outputwindow.

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Displaying the Volume MeshDisplay the mesh to permit its inspection in the existing displayer.

To display the volume mesh:

1. Select the Scenes > Geometry Scene 1 > Displayers > Geometry 1node.

2. To display the surface of the mesh, activate Mesh.

3. Right-click an empty part of the display and select Apply

Representation > Volume Mesh.

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This action reveals the mesh on the boundaries.


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Refining the MeshThe prism layer has been generated on the inner and the slip walls bydefault. Because a fluid boundary layer does not form on slip walls, youcan customize the prism mesh settings on that boundary.

To refine the mesh:

1. Select the Regions > subdomain-1 > Boundaries > Slip_wall >Mesh Conditions node and set Customize Prism Mesh to Disable.

To provide better definition of the blunt body, modify the surface meshat the inner wall:

2. Select the Regions > subdomain-1 > Boundaries > Inner_wall >Mesh Conditions > Custom Surface Size node and activate CustomSurface Size.

A new Mesh Values node appears.3. Select the Surface Size node and set Relative/Absolute to Absolute.4. Select the Surface Size > Absolute Minimum Size node and make

sure that Value is 0.0010 m.

To regenerate the mesh:

5.Click (Generate Volume Mesh).

6. Zoom in to the area around the slip walls and inner walls to see theimproved mesh.

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This mesh is satisfactory for an initial solution.7. Save the simulation.

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Selecting the Physics ModelsPhysics models define the primary variables of the simulation, includingpressure, temperature and velocity, and the mathematical formulation.

In STAR-CCM+, the physics models are defined on a physicscontinuum. In this example, the flow is turbulent and compressible. Youuse the Coupled Flow model together with the default K-EpsilonTurbulence model.

To select the physics models:

1. Right-click the Continua > Physics 1 node and choose Selectmodels....

The Physics Model Selection dialog appears as shown in the followingscreenshot.

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2. Select the Gas radio button from the Material group box, since this

exercise involves an idealized gas (air).

Since the Auto-select recommended models checkbox is activated, thePhysics Model Selection dialog guides you through the model selectionprocess by selecting certain default models automatically as you makesome choices.

Certain models, when activated in a continuum, require other modelsalso to be activated in that continuum. For instance, once a continuumcontains a liquid or a gas, it also needs a flow model. Once it has a flowmodel, it needs a viscous model (inviscid, laminar, or turbulent). Onceturbulence is activated within a fluid continuum, select a turbulencemodel. The prompt Additional model selections are required alertsyou to the fact that you have not completed the model selection.


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3. The following selections are required for this simulation:

a) Select Coupled Flow from the Flow group box.

b) Select Ideal Gas from the Equation of State group box.The Coupled Energy model is selected automatically.

c) Select Steady from the Time group box.

d) Select Turbulent from the Viscous Regime group box.

e) Select K-Epsilon Turbulence from the Reynolds-AveragedTurbulence group box.The Realizable K-Epsilon Two-Layer and the Two-Layer All y+Wall Treatment models are selected automatically.

To reverse part or all of the model selection process, simply clear thecheckboxes of the models you wish to deactivate. Other active modelsrequire the selections that are grayed out. Therefore, deactivate themodels that are not grayed out to begin with.

When complete, the Physics Model Selection dialog appears as shown inthe following screenshot:


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No optional models are required for this simulation.

4. Click Close.5. To see the selected models in the simulation tree, open the Continua

node in the bluntBody window of the Explorer pane.The color of the Physics 1 node has turned from gray to blue toindicate that models have been selected.

6. To display the selected models, open the Physics 1 node and thenthe Models node.


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You can view the model properties in the object tree.

When you select the Gas model, the properties of air such as dynamicviscosity are used by default. Since this problem uses air, the propertiesare acceptable.


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Setting Initial ConditionsInitial conditions in a continuum specify the initial field data for thesimulation.

Examples of initial conditions are:

• Pressure

• Temperature

• Velocity components

• Turbulence quantities

Each model requires sufficient information so that the primary variablesof the model can be set. For some models, such as turbulence models,the option of specifying the information in a more convenient form ispresented. For example, turbulence intensity and turbulent viscosityratio instead of turbulent kinetic energy and turbulent dissipation rate.

In steady-state simulations, the solution ought to convergeindependently of the initial field. However, the initial field still affectsthe path to convergence, and with it the cost in computing power.Therefore specify initial conditions and values judiciously, particularlywhen the physics is complex.

Specifying the Initial Conditions for the SimulationThe stagnation inlet boundary has conditions that correspond to a Machnumber of 0.75. The equivalent freestream velocity is roughly 300 m/s,the value you use to initialize the velocity field.

To specify the initial conditions:

1. Open the Continua > Physics 1 > Initial Conditions node.2. Open the Velocity > Constant node and set Value to 300,0,0.3. In the same Initial Conditions node, open the Turbulent Viscosity

Ratio node and select the Constant node.4. Set Value to 50, which is the same as the turbulent viscosity ratio

that is set on the stagnation boundary condition.5. Save the simulation.

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Defining the Region ContinuumYou can associate a continuum with zero, one, or more regions. Multiplecontinua can be defined and each region assigned a different one. In thistutorial, only one geometry part is present, which requires a singleregion to represent it, which was named subdomain-1. There is a simpleway to determine which set of continua models are allocated to a region.

To define the region continuum:

1. Select the subdomain-1 node in the Regions node.

2. Set the Physics Continuum property to Physics 1, the name of the

continuum where you defined all the models earlier.

During this tutorial, there is one continuum in the above drop-down list,but as you add more (to the Continua node in the simulation tree), theyare added to the drop-down list. This process determines whichcontinua is used in the analysis, though continua can be defined and leftunused.

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Setting Boundary Conditions and ValuesAlthough the concept of a boundary type is fairly unambiguous (wall,stagnation inlet, and so on.), models need more information to deal withthe type. Conditions provide this information.

For example, with a boundary of type wall, the conditions specifywhether this wall is to be a no-slip wall, a slip wall, or a moving wall.The conditions also tell you whether you want to apply a specifiedtemperature (Dirichlet) thermal boundary condition or a specified heatflux (Neumann) thermal boundary condition.

The types and conditions inform models how to deal with a boundary(or region or interface) but they do not specify actual numerical input.Values provide this input. Value nodes are added in response to choicesmade on conditions nodes.

Setting Inlet Conditions and ValuesSet the appropriate conditions and values for the Inlet boundary.

To achieve a Mach number of approximately 0.75 at the inlet, isentropicrelations were used to determine the inlet total pressure and outlet staticpressure for a given total temperature. For an outlet static pressureequal to one atmosphere (absolute) and a static temperature of 300 K,the inlet total pressure is 164,904 Pa (absolute). The inlet totaltemperature is 344.8 K.

The boundary values are specified as gauge pressures. Therefore, usingthe default reference pressure of 101,325 Pa (one atmosphere), set theinlet total pressure to 63,579 Pa (gauge). The outlet static pressure is 0 Pa(gauge), the default value.

To set the Inlet conditions and values:

1. Open the Regions > subdomain-1 > Boundaries node.2. Open the Inlet, Physics Values and Total Pressure nodes, and select

the Constant node.

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3. Set Value to 63579.

The total pressure setting is relative to the operating pressure value of101,325 Pa. A supersonic static pressure is also required as part of astagnation inlet condition but is only used if the inlet velocity becomessupersonic at some instance during solution iteration. The default valueof 0.0 Pa relative pressure is sufficient as long as supersonic flow doesnot occur.

The next value to set is the total temperature.

4. In the same Physics Values node, open the Total Temperature nodeand select the Constant node.

5. Set the Value to 344.8.6. Select the Physics Values > Turbulent Viscosity Ratio > Constant

node.

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7. Set Value to 50.

This value has been determined to give a reasonable decay ofturbulence in the channel core (for the default turbulence intensity).

Setting the Slip Wall ConditionTo simulate the body in a wind tunnel, the upper boundary is set to aslip wall, thus avoiding the need to resolve the boundary layer on thiswall.

To set the Slip Wall condition:

1. Select the Slip_wall > Physics Conditions > Shear StressSpecification node.

2. Set Method to Slip.

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Setting Solver Parameters and StoppingCriteria

Set the appropriate stopping criteria for the simulation.

To set the stopping criterion:

1. Select the Stopping Criteria > Maximum Steps node.

2. Set the Maximum Steps to 300.

The solution does not converge in this number of iterations. Thesolution does not run for more than 300 iterations, unless this stoppingcriterion is changed or deactivated.


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Visualizing the SolutionCreate a scalar scene to display the results of the simulation.

To watch the Mach number on the blunt body and vertical symmetryplane solution developing, set up a scalar scene.

To visualize the solution:

1. Right-click the Scenes node and select New Scene > Scalar.

A new Scalar Scene 1 display appears.

Hide all parts except the blunt body itself and the vertical symmetryplane.

2. Select the new Scenes > Scalar Scene 1 > Displayers > Scalar 1 >Parts node.

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3. Click the (Custom Editor) in the right half of the Parts property.4. In the Parts dialog, expand Regions > subdomain-1, select

Inner_wall and Symmetry_plane1, and click OK.

Define Mach number as the scalar to display:

5. Right-click the scalar bar (near the bottom of the Graphics window).6. Select Mach Number > Lab Reference Frame from the pop-up

menu.


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Since the geometry of this example is symmetric, the mesh was cut intoquarters with two symmetry planes to reduce computing costs.However, the symmetric repeat transform lets you create the visualeffect of the complete geometry by setting up the mirror image of themodel in the Graphics window. In this case, you only do one repeat sothat half the model is shown.

7. Select the Scalar 1 node.

8. Set the Transform expert property to Symmetry_plane2 1.


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To remove the outline:

9. Select the Displayers > Outline 1 node.10. Clear the checkbox of the Outline property.

The scalar scene appears as below.


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Monitoring Simulation ProgressSTAR-CCM+ can dynamically monitor a quantity of interest while thesolution develops.

The process involves:

• Setting up a report that defines the quantity of interest and theregion parts that are monitored

See Setting Up a Report.

• Defining a monitor using that report, which controls the updatefrequency and normalization characteristics

• Setting up an X-Y plot using that monitor

See Setting Up a Monitor and a Plot.

For this case, force is monitored on the body in the x-direction of theflow, which effectively is the total drag force. This process starts withthe report definition.

Setting Up a ReportCreate a report to collect the simulation results.

To set up a report:

1. Right-click the Reports node and select New Report > ForceCoefficient.

This action creates a Force Coefficient 1 node under the Reportsnode.

2. Select the Force Coefficient 1 node and enter the settings for thereport in the Properties window.

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a) Enter 1.277 for Reference Density, the density of the freestreamair.

b) Enter 264.6 for Reference Velocity, the velocity at the inlet.

c) Enter a value of 0.0161269 for Reference Area, the projectedarea of the quarter of the blunt body that is used in thesimulation.

d) Make sure that Direction is [1.0,0.0,0.0] (for drag).

Use the drag-and-drop method to select the monitored part, namely theInner_wall boundary:

3. Open the Regions > subdomain-1 > Boundaries node and then dragthe Inner_wall node onto the Force Coefficient 1 node.

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The Inner_wall entry is now listed in the Parts property of the ForceCoefficient 1 node.

The setup for the report is now complete, and a monitor and a plot canbe made from that report.

Setting Up a Monitor and a PlotCreate a monitor and a plot to display the report data.

1. Right-click the Force Coefficient 1 node and select Create Monitorand Plot from Report.

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This action creates a Force Coefficient 1 Monitor node under theMonitors node.

The existing monitors in this branch of the simulation tree are theresidual monitors from the solvers that the models use. With thenew monitor node selected, the default settings for the ForceCoefficient 1 monitor are seen.

These settings update the plot every iteration while the solution isrunning.

In addition to the new monitor node, a Force Coefficient 1 MonitorPlot node is created in the Plots node.


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2. Select the new Force Coefficient 1 Monitor Plot node.

The property settings for the plot appear.

Additional properties of the plot can be adjusted using the subnodes ofthe Force Coefficient 1 Plot node.

3. To view the plot display, do one of the following:

• Double-click the Force Coefficient 1 Monitor Plot node.

or

• Right-click the Force Coefficient 1 Monitor Plot node and selectOpen from the pop-up menu.

A Force Coefficient 1 Monitor Plot appears in the Graphics window.


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This plot display is automatically updated with the drag forcecoefficient when the solver starts to run.


The pre-processing setup is completed. The simulation can now be runto convergence.


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Running the SimulationPreparation of the simulation is now complete, and the simulation canbe run.

To run the simulation:

1. Do one of the following:

• Click (Run) in the Solution toolbar.

• Use the Solution > Run menu item.

The Residuals display is created automatically and shows theprogress of the solver. If necessary, click the Residuals tab to bringthe Residuals plot into view. An example of a residual plot is shownin a separate part of the User Guide. This example looks differentfrom your residuals, since the plot depends on the models selected.

The tabs at the top of the Graphics window allow you to select any oneof the active displays for viewing.

2. To see the results, click the tab of the Scalar Scene 1 display.3. Rotate and zoom if desired for a better view.

4. During the run, it is possible to stop the process by clicking (Stop)

in the toolbar.

If you do halt the simulation, you can resume it by clicking (Run).If left alone, the simulation continues until the stopping criterion of300 iterations is satisfied.

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5. After the run is finished, save the simulation.

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Adjusting Solver Parameters andContinuing

The default Courant number of 5 is conservative for this type ofproblem on a mesh of reasonable quality, so it can be increased toaccelerate convergence. When the solution has reached the stoppingcriterion of 300 iterations, adjust the solver parameters.

To adjust the solver parameters:

1. Select the Solvers > Coupled Implicit node and set CourantNumber to 10.0.

2. Select the Stopping Criteria > Maximum Steps node and set theMaximum Steps to 1500.

This setting instructs STAR-CCM+ to iterate 1200 steps in additionto the 300 already done.

The maximum number of 1500 steps is a reasonable setting, in this case,to get to convergence. Normally, you do not know ahead of time what asuitable iteration count is. You can either set a large iteration and watchthe residuals or a monitor plot, or add a stopping criterion from amonitor.

3. To continue running the simulation, click (Run).

Disconnecting and ReconnectingThe STAR-CCM+ client-server design permits you to run a simulation,disconnect the client from the running server, and then reconnect laterto check on results. You can also reconnect from a different machine,even a machine of another architecture.

To disconnect the client from the server:

1. Open the Servers window (if it is not already open) by selectingWindow > Servers.

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2. To see your simulation, look in the Servers window of the Explorer

pane.3. Reselect the simulation window in the Explorer pane, and select the

File > Disconnect menu item.

4. In the OK to disconnect dialog, click OK.

The client disconnects from the server, but both are still running,although the simulation window no longer appears in the client. Ifdesired, the client can be shut down using File > Exit.

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The Servers window of the Explorer pane lists all server processes(simulations) that are running locally.

5. Selecting the node in the tree displays the server process properties.

6. Continue by right-clicking the server process node in the Servers

tree and selecting Connect from the pop-up menu.

When you reconnect, none of the previously created scenes andplots are displayed in the Graphics window.

7. To display a scene of interest, do one of the following:

• Double-click its node in the simulation object tree.

or

• Right-click the node and select Open.

Completing the RunAt the end of the calculation, the Residuals display show most of theresiduals flattening out, which is a good indicator of convergence.

To confirm that the solution has converged:

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1. Select the Force Coefficient 1 Monitor Plot display to verify that thedrag coefficient has also flattened out.

2. Once the run is finished, save the simulation.

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Visualizing the ResultsView the results of the simulation using the scalar and vector scenes thatyou prepared earlier.

Once the solution is finished, you can examine the results in scalarscenes and vector scenes.

Examining ScalarsView the results of the simulation in a scalar scene.

To see the Mach number results for the finished solution:

1. Make the Scalar Scene 1 display active.

By default, Filled cell values are shown.

To display smooth contours:

2. Select the Scalar 1 node and set the Contour Style to (SmoothFilled).

The contours of the scalar display now appear smooth.

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Display two scalar values at the same time: one on the symmetry plane,the other on the inner wall:

3. Add another scalar displayer by right-clicking the Displayers nodeand selecting New Displayer > Scalar.

The creation of the second displayer has added a second scalar barin the display.

To view both scalar bars:

4. Point the mouse in the interior of a scalar bar to drag either one ofthem to a different location.

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5. In the display, right-click the scalar bar (blue) of the new displayer

and select Pressure.

6. Right-click the inner wall in the display, select Displayers, and open

its submenu.7. Among the checkboxes to the right of in, clear the checkbox under

Scalar 1 and tick the one under Scalar 2.


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This single step transfers the part from one displayer to another.8. Select the Scenes > Scalar Scene 1 > Displayers > Scalar 2 node.

9. Set the Contour Style to (Smooth Filled).10. Set the Transform expert property to Symmetry_plane2 1.

The blunt body shows pressure values while the symmetry planeshows Mach number.


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Examining VectorsThis section demonstrates how to examine velocity vectors in the model.In this example, you set up vectors in a reflected symmetry planearound a solid-colored blunt body.

1. First, create a scene by right-clicking the Scenes node.2. Select New Scene > Vector.

A new Vector Scene 1 display appears.

You do not need the outlines that the Outline part displayerprovides by default, so reuse that displayer to show the blunt bodyas a solid object.

3. Select the Vector Scene 1 > Displayers > Outline 1 > Parts node andclick (Custom Editor).

4. In the Parts dialog, click the column selection button twice.

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5. Expand the Regions and subdomain-1 nodes.6. Select the Inner_wall node.7. Click OK.

8. Select the Outline 1 node in the Displayers node.

9. Make the following changes to the Outline displayer properties:

a) Deactivate the Outline property.

b) Activate the Surface property.


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c) Set the Transform expert property to Symmetry_plane2 1.

10. Select the Vector 1 > Parts node and click the ellipsis (Custom

Editor) for the Parts value.

11. In the Parts dialog, expand the Regions and subdomain-1 nodes.

Select the Symmetry_plane1 node and click OK.


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12. Select the Vector 1 node.

13. Set the Transform expert property to Symmetry_plane2 1.

These settings show a solid blunt body with velocity vectorssurrounding it.


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It is possible to make the arrows shorter to see the vectors moreclearly.

14. Select the Vector 1 > Glyph > Relative Length node and changeGlyph Length (%) to 2.0.

The arrows now appear shorter.



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Plotting Data on a SliceCreate an x-y plot to visualize the pressure coefficient (on the y-axis)along a slice of the blunt body.

Creating the x-y plot requires the following steps:

1. Create a derived part for the slice.

2. Create a plot using the new derived part.

Creating a Derived PartCreate a plane section that cuts the blunt body. In STAR-CCM+terminology, this plane section is called a derived part.

To create the derived part:

1. Right-click the Scenes node and select New Scene > Geometry.

2. Right-click the Derived Parts node and select New Part > Section >

Plane....

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A new interactive in-place dialog is activated to allow definition ofthe derived part.

To define the source part for this derived part:

3. In the Input Parts group box, click [subdomain-1].4. In the dialog that appears, click the column selection button twice.5. Expand the Regions and subdomain-1 nodes.6. Select the Inner_wall boundary and click OK.

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The plane tool in the scene display allows interactive definition of theplane that cuts the blunt body.

7. Rotate and pan the image as needed so that the inner wall is in frontof the plane tool rectangle as shown.

8. In the dialog, leave the Display box at its default setting.


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The “barbell” represents the normal of the cutting plane, which canbe changed by dragging one of the balls to another location. Theplane can also be dragged to change the origin of the cutting plane.

A bounding box slightly larger than the regions in the scene is displayedto limit the movement of the plane.

9. Move the mouse over the plane tool, then click-and-drag therectangle so that it cuts the blunt body close to the symmetry plane.

The properties of the edit dialog are similar to those in the followingscreenshot:


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10. Click Create and then Close.

In the bluntBody window, a node, plane section, has been addedwithin the Derived Parts.


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It is now possible to plot data on the new surface.11. Save the simulation.

Plotting Simulation DataSet up a plot of pressure coefficients for the new derived part.

To create the plot:

1. In the bluntBody window, right-click the Plots node and select NewPlot > X-Y.

An empty plot node is added to the tree and opens in the Graphicswindow.

To select the part on which to plot:

2. Select the Plots > XY Plot 1 node and click (Custom Editor) for theParts property.

3. In the XY Plot 1 dialog, make sure that Derived parts > planesection is ticked.

4. Click OK.

To set the variable to plot on the y-axis:

5. Select the XY Plot 1 > Y Types > Y Type 1 node and make sure thatthe Type property is set to Scalar.

6. Select the Y Type 1 > Scalar node and set Scalar to PressureCoefficient.

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Match the reference density, reference pressure, and reference velocityof the Pressure Coefficient field function in the Force Coefficient 1report. Copy and paste these properties from the report to the fieldfunction:

7. Select the Reports > Force Coefficient 1 node.8. In the Properties window, select the value of the Reference Density

property, and press <Ctrl+C>.9. Select the Tools > Field Functions > Pressure Coefficient node.

10. In the Properties window, select the value of the Reference Density

property, press <Ctrl+V>, and then Enter.11. Repeat the above steps for the Reference Velocity.12. Leave the Reference Pressure property at 0.0 Pa.13. Select the Plots > XY Plot 1 > Axes > X Axis > Labels node then

ensure that Auto Range Min and Auto Range Max are selected.

The plot appears as shown below.


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Adding StreamlinesSet up a streamline derived part so that it shows the recirculating flowbehind the blunt body. Modify the part to show streamlines over theblunt body.

To visualize streamlines in STAR-CCM+, do the following:

• Create a scene.• Create a streamline derived part.• Add a streamline displayer, with suitable properties, to the new

scene based on the streamline derived part.

To create a scene and add streamlines:

1. Right-click the Scenes node and select New Scene > Geometry.2. Right-click the Derived Parts node.3. Select New Part > Streamline.

As with the plane section earlier, an interactive in-place dialogappears.

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The entire fluid region is used as the input part for the streamline part.

4. In the Input Parts group box, click the Select button.5. In the Select Objects dialog, make sure that subdomain-1 is the only

region selected.6. Click OK.7. In the Vector Field group box, make sure that Velocity is selected in

the drop-down list.8. For the seed mode, select Point Seed.


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To position the seed point just after the back of the blunt body (in thedirection of flow):

9. Enter the following coordinates under Seed Position:0.05 for X, 0.01 for Y, and 0.01 for Z

10. Enter 0.002 for Seed Radius and 10 for Number of Points.

11. Click Create.

After a few seconds, the streamlines are shown in the display.


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In the bluntBody window, a streamline node appears in the DerivedParts node.

12. Click Close in the interactive in-place dialog.

A new streamline displayer has been added to the scene.13. Select the Displayers > Section Stream 1 node to customize how the

streamlines appear:

a) Set the Mode to Tubes so that the streamlines are displayed astubes instead of lines.

b) Make sure that Orientation is set to Normals.

c) Specify Width at 2.0E-4, the width of the tube in meters.


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14. In the display, right-click the color bar and select Velocity:

Magnitude.

Improve the contrast between boundaries and streamlines:

15. Select the Geometry 1 node and set the Color Mode to Constant.

You now fine-tune the streamline derived part.


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16. Select theDerived Parts > streamline node and make sure that theRotation Scale expert property is 1.0.

17. Select the streamline > 2nd Order Integrator node and set theIntegration Direction to Both so that the streamlines are generatedboth upstream and downstream.

In the Expert properties:

18. Set Initial Integration Step to 0.1 to provide more resolution to thestreamlines.

19. Set Maximum Propagation to 5.0.20. Set Max Steps to 1000.

This option, together with the maximum propagation, provide astopping criterion to make sure that the streamlines are notcalculated endlessly.

The modified streamlines appear as below.

The next step involves moving the seed point of the streamline derivedpart to the front of the blunt body.

21. Select the 2nd Order Integrator node and change IntegrationDirection to Forward.

22. Select the streamline > Point Seed node and set the x-value of theCenter to -0.05, so that the value of the property is -0.05, 0.01,0.01.


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The modified streamlines appear in the display.



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Closing and Reopening the SimulationClose the simulation and reopen it again.

To close a simulation while it is running:

1. Close the bluntBody window.

The following dialog prompts you to choose whether to wait for theoperation to finish before closing the window, or close the windowand leave the operation to complete in the background.

2. Click Disconnect.

It is easy to reopen the file and restore the displays.

3. Select File > Recent Files > /bluntBody.sim.

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SummaryThis tutorial has introduced the following STAR-CCM+ features:

• Starting STAR-CCM+ and creating a simulation.

• Saving and naming the simulation.

• Importing a geometry file.

• Visualizing the imported geometry.

• Splitting and naming the geometry surfaces.

• Renaming techniques.

• Changing types of boundaries.

• Designing a three-dimensional mesh

• Visualizing the mesh.

• Selecting the physics models.

• Defining the initial conditions.

• Defining the boundary conditions and values.

• Setting the solver parameters and stopping criteria.

• Setting up a monitoring report and plot.

• Running the solver until the residuals are satisfactory.

• Disconnecting from a server and reconnecting during a run.

• Analyzing results using the visualization, monitor-plot, and XY-plotfeatures.

• Creating streamlines.

• Reopening a simulation.

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introduction 9.04

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