engineering solutions 11.0 tutorials

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Engineering Solutions 11.0

Tutorials


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Al tai r Engineer ing Contact Information

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HyperWorks11.0 Release Notes

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HyperWorks

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Engineering Solution 11.0 Tutorials iAltair Engineering

Proprietary Inform ation of Altair Engineer ing

Engineering Solutions 11.0 Tutorials

........................................................................................................................................... 1Engineering Solutions

............................................................................................................................................... 3CFD

................................................................................................................................... 4CFD-1000: Creating a Hybrid Grid using the CFD Mesh Panel

................................................................................................................................... 16CFD-1100: Creating a Hybrid Grid with Varying Boundary Layer Thickness

................................................................................................................................... 22CFD-1200: Generating a CFD Mesh with Automatically Adjusted Boundary Layer Thickness

................................................................................................................................... 33CFD-1300: Plane 2-D Meshing with Boundary Layers

................................................................................................................................... 45CFD-1400: Wind Tunnel Mesh

................................................................................................................................... 58CFD-1500: Hexcore Meshing with Boundary Layer

................................................................................................................................... 66CFD-1600: Using Distributed Thickness for Varying Boundary Layer Thickness

............................................................................................................................................... 77Crash

................................................................................................................................... 78CRASH-1000: Defining LS-DYNA Model and Load Data, Controls, and Output

................................................................................................................................... 91CRASH-1100: Using Curves, Beams, Rigid Bodies Joints, and Loads in LS-DYNA

................................................................................................................................... 106CRASH-1200: Model Importing, Airbags, Exporting Displayed, and Contacts using DYNA

................................................................................................................................... 114CRASH-1300: Rigid Wall, Model Data, Constraints, and Output using DYNA

................................................................................................................................... 124CRASH-2000: Front Impact Bumper Model

................................................................................................................................... 140CRASH-2100: Simplified Car Pole Impact

............................................................................................................................................... 153NVH

................................................................................................................................... 154NVH-1000: Acoustic Cavity


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Altair Engineering Engineering Solutions 11.0 Tutorials 1


Engineering Solutions

File Location Most tutorials use files that are located in the tutorials\directory of the

software installation. In the tutorials, file paths are referenced as

\..\.

Finding the Installa tion

Directory

In order to locate the files needed, you will need to determine the path of

the installation directory . This path is

dependent on the installation that was performed at your site. To determine

what this path is, follow these instructions:

1. Launch the application.

2. From the Helpmenu, select Updates.

The HyperWorks Update Informationdialog opens. The installation

directory path appears after Altair Home:.

The tutorial model files are located in\tutorials\es\.

Downloading Model Files If you are using the tutorials via the Altair website, you'll need to download

the model files before beginning. Access them by clicking:

http://www.altairhyperworks.com/hwhelp/Altair/hw11.0/index.aspx

Please note that a User ID and password is required to access this area.

Follow the instructions provided to obtain the login information.

See the full listing of available tutorials:

CFD User Profile Tutorials

Crash User Profile Tutorials

NVH User Profile Tutorials
http://www.altairhyperworks.com/hwhelp/Altair/hw11.0/index.aspx


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CFD

The following tutorials are available for the CFD user profile:

CFD-1000: Creating a Hybrid Grid using the CFD Mesh Panel

CFD-1100: Creating a Hybrid Grid with Varying Boundary Layer Thickness

CFD-1200: Generating a CFD Mesh with Automatically Adjusted Boundary Layer Thickness

CFD-1300: Plane 2-D Meshing with Boundary Layers

CFD-1400: Wind Tunnel Mesh

CFD-1500: Hexcore Meshing with Boundary Layer

CFD-1600: Using Distributed Thickness for Varying Boundary Layer Thickness


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Engineering Solutions 11.0 Tutorials4 Altair Engineering


CFD-1000: Creating a Hybrid Grid using the CFD Mesh Panel

In this tutorial, you will learn to:

Generate meshes for CFD applications (for example Fluent, StarCD) using the CFD Tetramesh

panel

Generate boundary layer type meshes with an arbitrary number of layers and thickness distribution

Specify / identify boundary regions for CFD simulations

Export a mesh with boundary regions for FLUENT

Import the model into FLUENT

Exercise

Step 1: Open the model file

1. From the toolbar, click Open Model .

2. Select the manifold_surf_mesh.hmfile from the tutorial directory.

3. Click Opento load this .hmfile containing the surface mesh.

Step 2: Load the CFD user profile

1. Click Preferences >User Profi les.

2. In the Applicationfield, select Engineering Solut ion s.

3. Select the radio buttonCFD.

4. Click OK.


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5. Inspect the surface elements that will be used to generate the volume mesh.

The boundary mesh can have any combination of tria/quad elements. You will generate boundary layers

on all the surface elements contained in the collector named wall.

Step 3: Check that all the elements in the collectors wal l, inlet, and outletsdefine a

closed volume

1. Click Mesh > Check > Compo nent > Edgesto open the Edgespanel.

2. Click the yellow compsbutton and select the collectors wall, inletand outlets.

3. Click select, and then click f ind edges.

A message indicating that no edges were found will appear on the statusbar.

4. Toggle the free edgesbutton to T-connections.

5. Select the three components again and then clickfind edges.

The statusbar will display: "No T-connected edges were found."

6. Click returnto close the panel.

Step 4: Create the CFD mesh

1. Click Mesh > Volu m e Mesh 3D > CFD tetramesh to open the CFD Tetrameshpanel.

2. Select the Boundary selectionsubpanel.

You will need to first select all the elements/components that define the surface area on which you need

to generate boundary layers. This is done by selecting the elements/components under the With

boundary layer (float)and With boundary layer (fixed) selectors.

3. Under the heading With boundary layer (fixed), click compsand select the collector wall.


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Next, select the remaining elements/components which define the volume but where a boundary layer is

not desired. This is done by selecting the elements/components under the W/o boundary layer (float)

and W/o boundary layer (fixed)selectors.

4. Under the heading W/o boundary layer (float), click compsand select the collectors inletand outlets

.

5. Verify that the switch below the W/o boundary layer (float)selector is set to Remesh. This means

that the meshes in the zones defined by collectors inletand outletswill be remeshed after being

deformed by the boundary layer growth from adjacent surface areas.

6. Leave the default Smooth BLoption unchanged.

This option is strongly recommended for most cases because it produces boundary layers with more

uniform thickness and better element quality.

7. Click the BL parameterssubpanel. All the data that has been entered in the Boundary selection

subpanel is stored.

8. Select the options to specify the boundary layer and tetrahedral core:

Number of Layers=5First layer thickness= 0.5

BL growth rate= 1.1(This non-dimensional factor controls the change in layer thickness from one

layer to the next).

9. Under the BL hexa transition modeheader, verify that selection is set to Simple Pyramid.

The default, Simple Pyramid, uses one pyramid element to transition from a BL hexahedrals quad face

to the tetrahedral core mesh.

10. Leave the Boundary layer onlycheckbox unchecked.

Thisoption generates the boundary layer alone and stops before generating the tetrahedral core. This

option modifies adjacent surface meshes to reflect changes introduced by the boundary layer thickness,

and creates a collector named ^CFD_trias_for_tetramesh, that is used to generate the inner core

tetrahedral mesh using the Tetramesh parameterssubpanel.

11. Click the Tetramesh parameterssubpanel.


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12. There are three different tetrameshing algorithms available. Select Optim ize Mesh Quality.

For a detailed explanation of each option, please refer to the online help.

13. Set the tetrahedral core growth rate, interpolate.

This avoids the problem of generating tetrahedral elements that are too large at the center of the core

mesh.

14. Clickmeshto create theCFD mesh.

When this task is finished, two collectors are automatically created: CFD_boundary_layer and

CFD_Tetramesh_core.

.

15. Click return to close the panel.

Step 5: Mask some of the mesh to view the interior elements and boundary layers

1. You can mask the mesh by using the shortcut key F5, and select elements to be masked.

Following is a snapshot. Observe the excellent mesh quality produced.

2. You can also use the Hidden Linepanel to view the interior of a solid mesh. Click BCs > Check >

Hidden Linesto access the panel.

3. Leave the titlefield blank and check the option for yz plane.

This defines the yz plane as the cutting plane.

4. Leave the options for trim planesand clip boundary elementschecked on and click show plo t.


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This automatically places the cutting plane at the center of the model. Notice that the display of the

elements has been collapsed so that the nodes lie on the cutting plane.

5. Left-click in the graphics area where the cutting plane is, hold down the left mouse button, and drag the

mouse. Notice that the cutting plane moves.

6. Next, uncheck the option for clip boundary elementsand click show plo t.

Notice how the elements are displayed completely.

7. Drag the placement of the cutting plane. Experiment with the other cutting planes and the trim planes

option to see how they affect the plot.

8. Click returnto exit the panel and clear the plot.

Step 6: Organize the model

In this section, you will define mesh surface regions used to specify boundary conditions in any CFD code

( FLUENT, StarCD, CFX, etc). For example, assume that you are going to export the mesh for FLUENT. For

this model, you need to create three collectors to place the boundaries: inflow, outflow, and wall. You

have selected two new names that are not already in your database and at the same time are compatible

with the prefixes required by FLUENT to recognize boundary types according to their names.

You are going to reuse the surface mesh contained in collector wallbecause this mesh remained

unchanged by the CFD mesh process as this component was specified as fixed with boundary layer.


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However, the surface areas associated with the original collectors inletand outletshave been completely

regenerated and you need to create new components that will be named inflowand outflow, respectively.

1. Rename the collector CFD_Tetramesh_coreas fluid.

This collector will hold all the 3-D volume elements.

2. Click BCs > Organi ze to move all the elements from the collector CFD_boundary_layerto collector

fluid.

3. Click BCs > Facesto automatically generate the collector ^facescontaining all the external faces of the

elements in collector fluid.

4. Click BCs > Comp onent > Singl e to create two new components named inflowand outflow.

Now you are going to move some of the elements from the collector ^faces to the collectors inflowand

outflow.

5. In the Model Browser, isolate the facescomponent.

6. Click BCs > Organizeand click one element on the inlet/inflowplane (the element will become

highlighted).

7. Click elems >> by face.

All the elements in the collector ^faceson the inlet/inflow plane will be selected.

8. Set the dest compas in f low, and click move. Similarly, move the elements from ^facesassociated

with the outlets to the collector outflow.

9. Show the inflowand outflowcomponents in the Model Browser.

When done, you will have all the exterior surfaces colored according to the collectors where they have

been placed as shown in the following image.


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10. The remaining elements in the collector ^facesare the same as in walland you can discard them.

11. Delete both collectors ^facesand collector CFD_boundary_layer, which is now empty.

Step 7: Export surface and volume mesh and import this mesh into FLUENT

1. Display only the components containing elements that have to be exported for FLUENT, the components

are: fluid, inflow, outflow, and wall. All other components should not be visible.

2. Click the Expo rt Solv er Deck icon to open the Exporttab.

3. Notice that the File Type is set to CFD. Set the Solver Type to Fluent.

4. In the Filefield, click on the file icon and specify a name and location for the file.

5. Click Expor tto export the file.

Step 8: Create a FLUENT simulation case

If you have access to FLUENT, you can import manifold.casto create a new FLUENT simulation case asfollows

1. Start FLUENT 3dor 3ddp.

2. From the Fi lemenu, select Read, then Case....

3. Select manifold.cas.

4. Click OK.


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After importing this file, you will observe that FLUENT has recognized the boundary zones outflow,

inflow , and wallby name, and the 3-D volume zone fluid. Zone interior-*is automatically created by

FLUENT containing all the interior faces shared by two 3-D cells.

5. Select Define, then select Boundary Condi t ion s.

6. Select zoneinf low, and set the appropriate boundary condition such as mass-flow-inlet and velocity

inlet.

7. Change the boundary condition type for the remaining surface zones,out f low and wall.

Engineering Solutions allows you to perform the most time consuming tasks of generating the volume mesh

and identifying the boundary zones. Now inside FLUENT the rest of the simulation tasks can be executed

easily.


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Appendix: Boundary Layer Mesh with Distributed Thickness Ratio

The boundary layer type mesh generated in this tutorial was generated with uniform thickness. This is OK for

a model like this manifold as long as the total boundary layer thickness does not lead to collision or

interference that can occur when the sum of the BL thickness is close to or larger than the distance

separating boundary layer walls. When such collision or interference occurs you have the following options:

Decrease the global boundary layer thickness (throughout / for all the BL surfaces)

Use distributed boundary layer thickness ratios on nodes or collectors/components. This is a

capability in HyperMesh that allows you to specify a local value of boundary layer thickness by

specifying the ratio of the local value to the global value. For example, if the ratio specified on certain

nodes or all the nodes belonging to a collector is equal to 0.1, then the boundary layer thickness

generated around those nodes will be only 10% of the global boundary layer thickness.

The CFD User Profile has a tool (Generate BL Thickness) to generate automatically distributed

boundary layer thickness ratios at each node of the surface mesh so that boundary layer collision is

avoided when using the global or nominal boundary layer thickness. The usage of this tool is

explained in Tutorial HM-3240.

In this appendix you are going to use option B to manually change the BL thickness ratio.

Step A: Prepare data to generate a CFD mesh (boundary layer and core mesh)

using a distributed boundary layer thickness.

1. Create a new component named wall_thinner_bl, and move elements from wall to this new collector as

shown in the following image.

2. Click BCs > Check > Ed ge, then select the collectors wall, wall_thinner_bl, inletand outlets.

3. Click f ind edges. A message indicating that no edges were found will appear on the status bar.

4. Click Mesh > Vo lum e Mesh 3D > CFD tetram eshto access the CFD Tetrameshpanel.


6. In the BL parameters subpanel, select the options to specify the boundary layer and tetrahedral core:

Number of Layers= 5

First layer thickness= 0.5

BL growth rate= 1.1


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7. Select the type of tetrameshing algorithm: Simple Pyramid, Smooth Pyramid, All Prism, orAll

Tetras

8. Ensure the Boundary layer onlycheckbox is not checked.

9. In the Tetramesh parameters subpanel, set the Pyramid transition ratio=0.8

10. Select the tetrahedral core growth rate switch to Interpolate.


mesh.

Step B: Define a distributed boundary layer thickness on certain components.

1. In the BL parameterssubpanel, ensure the BL reduction checkboxis checked and click the green

Manualbutton.

2. The Distributed BL Thickness Ratiodialog opens. This dialog enables you to specify distributed

thickness ratios for groups of nodes or whole components. You can choose either nodesor

componentsby selecting the associated radio button.

3. Click the Components radio button.

4. Click the yellow Select Com pon ents button and select the component wall_thinner_bl.

5. Specify a thickness ratio of value0.3and click Assign.

6. Notice that the summary message now indicates the number of BL thickness ratio loads oncomponents:


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When the models are more complex it is useful to display surface contours of BL thickness ratio values.

7. Click Contours of BL Thick ness Ratio, and the Contourpanel will be automatically displayed.

8. Press contourto inspect the distribution of BL Thickness Ratio on the surface of your domain. Click

Closeto close the dialog.

9. Go to the CFD Tetramesh panel, Boundary selectionsubpanel. Here all the elements/components

that define the surface area on which you need to generate boundary layers will be selected. This

selection is done with the With boundary layer (fixed) selector.

10. Click compsunder With boundary layer (fixed)and select the collectors walland wall_thinner_bl.

11. Select all the elements/components that define the surface area on which you do not want to generate

boundary layers. This selection is done with the W/o boundary layer (float)selector.

12. Click compsand select the collectors, inletand outlets.

13. The switch below the W/o boundary layer (float)selector is set to Remesh.This means that the

meshes in the zones defined by collectors inlet and outlets will be remeshed after being deformed by the

boundary layer growth from adjacent surface areas.

14. Click meshto create the CFDmesh.

When this task is finished, note the two collectors automatically created: CFD_boundary_layer and

CFD_Tetramesh_core.

15. Inspect the relative size of the boundary layer thickness by masking some of the elements as shown in


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the following image. This image shows that the BL thickness on component wall_thinner_blis only

30% of the global BL thickness.

The manual approach followed previously is useful when you need to reduce the BL thickness throughout

a component, or at a clearly identified group of nodes.

When you have a very complicated geometry and BL collision is likely to occur, the best approach is to

use the Generate BL Thicknesstool to generate automatically distributed boundary layer thickness

ratios at each node of the surface mesh. This tool performs a collision study and assigns a BL

thickness ratio to each node of the surface mesh that requires a reduction of the baseline BL thicknessto avoid collision. Usage of this tool is explained in Tutorial CFD-1100.

The previous steps illustrate simple and effective steps to reduce the BL thickness on surface components.

This approach is very easy to use and effective when you know how much you want to increase or decrease

the BL thickness all over a component. A similar approach is followed to increase/decrease BL thickness on

groups of nodes.


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CFD-1100: Creating a Hybrid Grid with Varying Boundary LayerThickness


Generate boundary layer type meshes with an arbitrary number of layers and thickness distribution,which can be used for CFD applications, molding simulations, or other processes.

Generate automatically a distributed thickness distribution to prevent boundary layer interference /

collision in zones where the distance between opposing walls is too small to accommodate the

baseline or nominal boundary layer thickness.

Exercise


1. Click Preferences >User Profi les.

2. In the Applicationfield, select Engineering Solut ion s.

3. Select the radio buttonCFD.

4. Click OK.

Step 2: Open the model file


2. Select the molding1.hmfile from the tutorial directory.

3. Click Opento load this .hmfile containing the surface mesh.



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The boundary mesh can have any combination of tria/quad elements. You will generate boundary layers

on all the surface elements contained in the collector named wall.

Step 3: Check that all the elements in collector wal ldefine a closed volume

1. Click Mesh > Check > Com pon ents > Edgesto open the Edgespanel.

2. Click compsand select the collector wall.

3. Click f ind edges.

A message indicating that no edges were found will appear on the status bar.

4. Toggle free edgesto T-connections.

5. Select the collector wall again and clickfind edges.

The status bar will display, No T-connected edges were found.

Step 4: Create the CFD mesh

1. Click Mesh > Volu m e Mesh 3D > CFD Tetra mesh to open the CFD Tetrameshpanel.


You will need to first select all the elements/components that define the surface area on which you need

to generate boundary layers. This is done by selecting the elements/components under the With

boundary layer (float)selector.

3. Under the heading With boundary layer (float), click compsand select the collector wall.

4. Verify that the switch below the W/o boundary layer (float)selector is set to Remesh. This means

that the meshes in the zones defined by the collector wallwill be remeshed after being deformed by the

boundary layer growth from adjacent surface areas.


This option is strongly recommended for most cases because it produces boundary layers with more

uniform thickness and better element quality.


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6. Click the BL parameterssubpanel. All the data that has been entered in the Boundary selection

subpanel is stored.

7. Select the options to specify the boundary layer and tetrahedral core:

Number of Layers =5First layer thic k ness = 0.5

BL gro wth rate= 1.0(This non-dimensional factor controls the change in layer thickness from one

layer to the next).

8. Under the BL hexa transition modeheader, change the selection to A ll Prism s (Prism s to all Layers).

This means that if there are any quad elements in the surface mesh, those will be split into two trias

each so that there is no need to transition from quad faces to tria faces when transitioning from the last

boundary layer to the tetrahedral core. This option is very important when there are quad elements on

areas with (low) distributed BL thickness ratio, because in such areas the thickness of the transition

elements (e.g., simple pyramid) was not taken into account when doing the interference study to assign

distributed BL thickness ratio to those elements.

9. Leave the Boundary layer onlycheckbox unchecked.

Thisoption generates the boundary layer alone and stops before generating the tetrahedral core. This

option modifies adjacent surface meshes to reflect changes introduced by the boundary layer thickness,

and creates a collector named ^CFD_trias_for_tetramesh, that is used to generate the inner coretetrahedral mesh using the Tetramesh parameterssubpanel.

10. Click the green Autobutton.

11. In the Generate Boundary Layer distributed thickness valuesdialog, click Ad d col l ectors with

surface elements.

12. The components selection subpanel opens.

13. Select the collector wall, and then click proceed.

14. Specify the Boundary Layer optionsas shown in the following image.

- The number of layers, first layer thickness and growth rate have been established in the BL


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parameters subpanel and are greyed out here. All layers will have the same thickness (except for

mesh smoothing operations such as hyperbolic smoothing at corners).

- Specify a Minimum Tetrahedral Core / Boundary Layer thickness ratiovalue of 0.5.

This means that in areas where there is not enough room to grow the nominal BL (3 layers of 0.5

each), the boundary layers thickness will be reduced so that the tetrahedral core thickness is at

least 0.5 times the total boundary layer thickness, except for mesh smoothing operations such ashyperbolic smoothing at corners, and convex/concave areas.

- The last opt ion, Bound Layer thickness at corners, is a coefficient that controls the hyperbolic

growth where walls make an angle. The smaller this value is, the thinner the total BL thickness in

such areas is.

Now you are ready to generate the Distributed BL Thicknessloading. Make sure that none of the

elements specified in the boundary collectors are masked. If they are masked an error message will

indicate that there is a discrepancy between the total number of elements in the components and the

tria3/quad4 elements found. If you have masked elements, you can access the Mask(F5), and press

unm ask al l.

15. Click Generate Distributed BL Thickness Ratio.

16. If the model already contains boundary layer thickness ratios, then a pop-up message box will ask you if

you want to keep such loading or if you want to delete them. Most of the time you will want to clear the

existing boundary layer thickness ratios; press Yes. In some special cases you may want to keep them,if more than one loading value is specified at a node, the minimum value is used when generating the

mesh.

After a few seconds you will see a pop-up message indicating the number of distributed boundary layer

thickness values included in collector ^CFD_BL_Thickness.

17. Click Close in theGenerate Boundary Layer distributed thickness valueswindow.

18. Click the Tetramesh parameterssubpanel.


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19. There are three different tetrameshing algorithms available. Select Optim ize Mesh Quality.

For a detailed explanation of each option, please refer to the online help.

20. Set the tetrahedral core growth rate, interpolate.


mesh.

21. Clickmeshto create theCFD mesh.

When this task is finished, two collectors are automatically created: CFD_boundary_layer and

CFD_Tetramesh_core.


Step 6: Mask elements to inspect the boundary layers thickness on thinner areas

1. Access the Maskpanel by using the shortcut key F5.

2. Select elements to be masked.

3. Click mask.

The following images illustrate how BL interference has been avoided by reducing the BL thickness.


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Step 7: Generate a pure tetrahedral mesh for moldflow.

The mesh needs to consist of tetrahedral elements only. This was accomplished by generating tetras directly

in the boundary layer. However, if you need to split penta / wedge elements into tetras, use the procedure

below.

1. Click Mesh > Edi t > Elements > Spli t Elements.

2. Select the solid elementssubpanel.

3. Set the switch to split in to tetras.

4. Select elems >>by co l lector and selectwall.

5. Click spl i t.

Now you have a mesh consis ting of tetrahedral elements only.

The objective of this tutorial is to illustrate how you can generate very thin boundary layers without

interference. However, such thin boundary layers can lead to element with a high aspect ratio if the size of

the surface mesh is not small enough. If you need to limit the tetrahedral elements aspect ratio (e.g., < 5),

then you need to use a fine enough mesh on the wallcomponent so that thin boundary layers do not

produce high aspect ratio elements. For example, in this case, the minimum value oftetra collapseof all

tetrahedral core elements was 0.2, but after you split the BL penta / wedge elements into tetras, the

minimum value of tetra collapseof all tetrahedral elements becomes 0.04. This occurs because the BL penta

elements are thin compared to their triangular face area size.

Summary

HyperMesh allowed you to generate high-quality boundary layer meshes on parts with very thin walls. To

accomplish this you first need to use the utility Generate Distributed BL Thickness Ratioto generate load

collector ^CFD_BL_Thickness. This load collector is then used when you enable distributed thickness. As

shown in the cross-sectional images, the mesh is very smooth and is of excellent quality.


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CFD-1200: Generating a CFD Mesh with Automatically AdjustedBoundary Layer Thickness

Mesh generation in domains bounded by surfaces that are very close to one another in some

areas.


Generate meshes for most CFD codes (e.g. Acusolve, CFD++, CFX, Fluent, StarCD, SC/Tetra)

using the CFD Tetramesh panel.

Generate boundary layer type meshes with arbitrary number of layers and thickness distribution in

domains defined by surfaces that are very close to one another in some areas. More specifically, in

some areas the clearance or separation of bounding surfaces is not enough to accommodate the

user specified nominal boundary layer thickness.

Generate a distributed thickness loading that prevents boundary layer interference / collision in

zones where the distance between opposing walls is too small to accommodate the baseline or

nominal boundary layer thickness.

Exercise

Step 1: Open the exercise file


2. Select the manifold_inner_cylinder.hm file from the directory

\tutorials\es\cfd .

3. Click Opento load this file containing the surface mesh.


You would like to generate boundary layers on all the surface elements contained in components wall

and wall_cyl. However, there is an area close to the end of wall_cylwhere the clearance between wall

and wall_cylis very small. This can be easily observed in this case by changing the visibility of

component wallas shown, following.


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In more complex models it is not possible to visually identify all the zones where there is not enough

space to growth the baseline or nominal boundary layer as specified in terms of the number of layers,

first layer thicknessand growth rate. This is not a problem because the automatic distributed

thickness loading computation takes into account all possible interference cases. This is demonstrated

in this tutorial.

Step 2: Check that the surface elements define a closed volume

1. Click Mesh > Check > Com pon ents > Edges.

2. Click comps and select all collectors that define the domains surface, namely inlet, outlets, walland

wall_cyl.


A message indicating that no edges were found will appear on the status bar.

4. Toggle the free edgesswitch to T-connections.

5. Select the components again and clickfind edges.

The status bar will display, No T-connected edges were found.

Step 3: Generate a BL distributed thickness loading to prevent boundary layer

interference

1. Click Mesh > Vo lum e Mesh 3D > CFD tetram esh.


3. Under the heading With boundary layer (fixed), click compsand select the collectors walland

wall_cyl.

4. Under the heading W/o boundary layer (float), click compsand select the collectors inletand outlets


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.

5. Ensure that the switch below the W/o boundary layer (float)selector is set to Remesh. This means

that the surface meshes associated with those components will be remeshed or rebuilt after shrinking

due to boundary layer growth from adjacent boundary layer components.


7. Click theBL parametersubpanel.

8. Set the following fields:

Number of Layers= 5

First layer thickness= 0.5

BL growth rate= 1.2(This non-dimensional factor controls the change in layer thickness from one

layer to the next).

BL quad transition= A ll Prism s (Prism to all L ayers).This means that if there are any quad

elements in the surface mesh, those will be split into two trias each so that there is no need to

transition from quad faces to tria faces when transitioning from the last boundary layer to the

tetrahedral core. This option is very importantwhen there are quad elements on areas with (low)

distributed BL thickness ratio, because in such areas the thickness of the transition elements (e.g.,

simple pyramid) was not taken into account when doing the interference study to assign distributed

BL thickness ratio to those elements.

9. Click the green Autobutton. The Generate Boundary Layer distributed thickness values dialog

opens.

10. Click Add co llectors with surface elem ents. The component selection panel opens.

11. Select all the collectors that define the volume surface, namely inlet, outlets, walland wall_cyl, and

then click proceed.

12. The Generate BL Thick nesswindow will show the components selected as shown, following:


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13. Set the correct Bound Typefor each one of the selected components. You want to generate a boundary

layer from components walland wall_cyl, therefore, you will leave wallas their Bound Type. Also

verify that the Bound Typeof components inlet and outletsis set to in/out letas shown, following:


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Note:

A component with Bound Type: wallindicates that you are going to generate a boundary layer mesh

on the component later on when you generate the mesh. Therefore, the same component should be

consistently specified with the comps selector for the Withboundary layer (fixed orfloat)in the

Boundary selectionsubpanel.

A component with a Bound Type:slip, symmetry, in/outlet, or farfieldindicates that you are NOT

going to generate a boundary layer mesh on the component. Therefore, when you generate the mesh thiscomponent should be consistently specified with the comps selector for the W/oboundary layer

(fixed orfloat)in theBoundary selectionsubpanel.

14. Specify the Boundary Layer optionsas shown in the following image.

The first three fields are set in the BL parameters subpanel and cannot be changed here. All layers

will have the same thickness except in area affected by the distributed thickness "loading" and also

mesh smoothing operations such as hyperbolic smoothing at corners.

Specify a Minimum Tetrahedral Core / Boundary Layer thickness ratiovalue of 2.0. This

means that in areas where there is not enough room to grow the nominal BL (5 layers starting with a

thickness of 0.5 and increasing with a grow rate of 1.2), the boundary layers thickness will be

reduced so that the tetrahedral core thickness is approximately at least 2.0 times the total boundary

layer thickness, except for mesh smoothing operations such as hyperbolic smoothing at corners and

convex/concave areas.

The last option, Bound Layer thickness at corners, is a coefficient that controls the hyperbolic

growth where walls make an angle. The smaller this value is, the thinner the total BL thickness is in

such areas; values less than 1 produce thinner layers and values greater than 1 produce thicker

layers.

Now you are ready to generate theDistributed BL Thicknessloading. Make sure that none of the

elements specified in the boundary collectors are masked. If they are masked an error message will


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indicate that there is a discrepancy between the total number of elements in the components that you

specified and the number of tria3/quad4 elements found (displayed). If you have masked elements, you

can use mask(F5), and press unm ask al l.

15. Click Generate Distribu ted BL Thi ck ness Ratio.

If the model already contains boundary layer thickness ratios, then a pop-up message box will ask you ifyou want to keep such loads or if you want to clear/discard them. Most of the time you will want to clear

the existing boundary layer thickness ratios; press Yes. In some special cases you may want to keep

them, if more than one loading value is specified for a node, the minimum value is used when generating

the mesh.

16. After a few seconds you will see a pop-up message indicating the number of Distributed Boundary Layer

Thickness Values included in collector ^CFD_BL_Thickness.

17. Click Closein the Generate Boundary Layer distributed thickness valueswindow.

Step 4: Generate the boundary layer and tetrahedral core mesh

1. In the CFD Tetra Meshpanel, click theTetramesh parameterssubpanel.

2. Set the switch for the tetrahedral mesh generation algorithm to Opt imize m esh qual i ty.

3. Ensure the tetrahedral grow rate is switch to interpolate.

4. Click meshto generate themesh. If collectors CFD_boundary_layer and CFD_Tetramesh_core are

present, you will be asked if you want to delete the elements in those collectors. Almost always youselect Yes.

When this task is finished two collectors are created: CFD_boundary_layer and

CFD_Tetramesh_core.


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Step 5: Mask elements to inspect the boundary layers thickness on thinner areas

1. Select the xz Left Plane View icon .

2. Access the Maskpanel by using the shortcut key F5.

3. Select elements to be masked by pressing SHIFT and the left mouse button, then move the cursor so

that the rubber band covers the upper half of the model.

4. Click mask.

5. Click the xy Top Plane View icon

6. Zoom in into the area where the bounding surfaces come close together. The following image illustrateshow BL interference has been avoided by reducing the BL thickness.

7. Click returnto close the Mask panel.


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Step 6: Arrange volume and surface components before exporting the mesh for

CFD solvers

First you need to put in the same component all the elements that represent a single fluid and/or solid

domain. In this case you have a single fluid domain, therefore you proceed as follows:

1. Rename the CFD_Tetramesh_corecomponent. Typically, select a name fluid*, for example,

fluid. In the Model Browser, select CFD_Tetramesh_core, right-click, select Rename, and then

type the new name, fluid.

2. Click BCs > Organize.

3. Click elems >> by col lectorand select the collector CFD_boundary_layer.

4. In the dest componentfield, select f lu id.

5. Click move and then click return.

Now you have all the volume elements in component fluid. The surface mesh of this component is

typically different from the surface mesh that was used to define the boundary of the domain. For this

reason, and to have consistent surface zones to impose boundary conditions in most CFD solvers, you

are going to create new boundary components that will be used when exporting the mesh for the CFD

solver of your choice. To accomplish this you first extract the surface mesh of component fluid. You do

this by generating the surface elements.

6. Click BCs > Faces.

7. Select the component fluid, and click f ind faces. All boundary faces are placed in the component

^faces.

8. Create new, empty components to place the elements from ^facesso that when these components are

later exported, they can be used to set a boundary condition in your CFD solver. In the Model Browser,


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right-click on Component, and then select Create.

9. Enter the name as wall_exterior. Leave Card imageas none, and click Create.

10. Create 3 more empty components with the names wall_cylinder, inlet_annulus, and outlets3.

11. Move the elements from component ^facesinto the newly created components. This is done for clarity;

however, most of the time you create one fewer component and you rename^faceswhich retains the

remaining elements after you move elements to the newly created surface components. Organize the

components by using the Organize panel. SelectBCs > Organize.

12. Set dest componentto wall_exter ior, then pick one element on the exterior wall surface in the ^faces

component.

13. Click the elemsswitch and select by face.

This will recursively select all the elements attached to the picked element as long as the adjacent

elements are within a break angle less or equal to the value specified in the feature anglefield (

Preferences> Geometry Option s> Meshsubpanel).

The surface mesh in ^facesis such that the zones that you want to organize/move make an angle close

to 90 degrees and their boundaries, therefore this is a very easy job to do with a default feature angle of

20 or 30 degrees.


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16. Having selected all the elements that should go to component wall_exterior, click move.

17. Now set the destcomponent tooutl ets3and pick at least one element on each one of the three

separate outlets as shown in the following image.

18. Click the elemsswitch and select by face.

19. Having the elements on the three outlets selected, press moveand those elements are moved to

component outlets3.

20. Set dest component to in let_annulusand pick one element as shown in the following image.

21. Right-click the elemsswitch and select by face.

22. Having all the elements on the inlet annulus selected, press moveand those elements are moved to

component inlet_annulus.

Now that all the remaining elements in component ^facesare the elements that you want to move to

component wall_cylinder.

23. Set dest component to wal l_cyl inder.

24. Click on elemsand in the panel area and select by col l ector.

25. Select the component ^faces.

26. Click move and then click return.

The elements are moved to component wall_cylinderas shown in the following image.


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As mentioned previously, more often than not it is easier to rename/recolor component ^faces.

Step 7: Exporting the mesh

1. Verify that only the components that you want to export are displayed. All other components should NOT

be displayed, as illustrated in the following image of the Model Browser.

2. Click the Export Solver Deckicon to open the Exporttab. Select the CFD file format of your

choice (such as Acusolve, CFD++, CFX, CGNS, Fluent, or StarCD) to export the grid or mesh.

Note:solvers like Acusolve and FLUENT have certain requirements when the domain contains different

fluids and/or solids. This is described in other sections of the Engineering Solutions Help system.

Summary

Engineering Solutions allowed you to generate high-quality boundary layer meshes on parts where the

clearance or separation of the bounding surfaces is not enough to accommodate the user specified nominal

boundary layer thickness. To accomplish this you first used the CFD utility Generate Distribu ted BL

Thi ck ness Ratioto generate load collector ^CFD_BL_Thickness. This load collector is then used when you

enable distributed thickness. As shown in the cross-sectional images, the mesh is very smooth, free of

collisions, and is of excellent quality.


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CFD-1300: Plane 2-D Meshing with Boundary Layers

2-D Boundary Layer Mesh generation in domains bounded by edges


Generate 2-D boundary layer type meshes with an arbitrary number of layers and thickness

distribution in domains defined by edges.

Generate 2-D boundary layer type meshes in areas where the clearance or separation of bounding

edges is not enough to accommodate the user specified nominal boundary layer thickness / number

or layers.

Exercise


1. Click Fi le> Open.

2. Navigate to the directory \tutorials\es\cfd and select the

manifold_inner_cylinder_2d.hm file.

3. Click Opento load the file containing the edges.

4. Inspect the edges elements that will be used to generate the volume mesh.

The boundary mesh should only consist of PLOTEL (elem type) elements. You want to generate

boundary layers on all the edges contained in the collectors called walland inner wall.

Step 2: Check that all the elements in collectors wall, inner wall, inlet, and outlets

define a closed loop. (This step is for info rmation o nly; it is option al for this tuto rial)

Usually, this step is not necessary because the collectors containing edge elements (PLOTEL) are extracted

from 2-D surface meshes that naturally have free edges forming closed loops. However, there is a possibility


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that there may be duplicate nodes, and for this reason it is advisable to perform the following test:

1. Click BCs > Check > Ed ge.

2. Click comps.

3. Select the collectors wall, inner_wall, Inlet, and Outlet.

4. Click select.

5. You need to ensure that the tolerance value is smaller than the minimum element length. To do this, first

find the minimum element length.

Click Mesh> Check >Elements >Check Elements.

6. Select the radio button 1-d.

7. Click the top length button.

A message indicates the minimum element length is 3.09, therefore you can safely use a tolerance of 3.

8. Click returnto close out of the current panel.

9. In the Edge panel, enter 3.0in the tolerance =field and then click Preview Equ iv. A message

indicating that 0 nodes were foundwill appear on the status bar.

Step 3: Generate a 2-D BL Mesh

1. Click Mesh > Surface Mesh 2D > 2D Mesh wi th BL .

2. Click the 2D Native BL (planar)tab.


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11. Default values of boundary layer mesh (1st LayerThickness, Growth Rate, and Bound Type) will be

assigned to each component. To remove one or more components from the group, select those

components from the list and press Remove.

12. In the 2D Boundary Layer Meshwindow, set the Bound Typevalue for components Inletand Outlet

as In/Outlet.

The objective is to not generate boundary layers along the Inletand Outletcomponents.

Note:those elements may be remeshed based on the adjacent elements size.

13. Click Generate 2D BL Meshto generate the mesh.

When this task is finished, two collectors are automatically created: 2DBLMeshand 2DCoreMesh, as

shown in the following image. Note that the quality of the mesh may not be very good, as described,

following. In the next steps you will change some default parameters to allow boundary node insertion

and movement.


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As indicated previously, components with Boundtype In/Outletwill be remeshed based on the adjacent

elements size. The two following figures illustrate the case where an inlet/outlet is defined with a single

large element, after meshing the element size in this area has been reduced to obtain a smooth element

size transition, leading to and excellent mesh quality.


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Step 6: Changing Mesh Quality

Often it may happen that boundary layer elements will have bad quality due to high aspect ratio. Such

elements are created because of the large boundary edge length as shown in the following image.

This problem can be resolved by limiting the maximum perimeter elements aspect ratio. The maximum

boundary elements aspect ratio can be achieved using two approaches:

By addition of new nodes on the boundary / perimeter.

By node movement on the boundary / perimeter.

1. Activate the Allow boundary node insertioncheckbox.

- Refine the boundary edges by insertion of nodes on boundary edges. New node insertion is

controlled by the specified maximum perimeter element aspect ratio.


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Or

- Activate the Allow boundary node movementcheckbox.

This option is used to move boundary nodes along the original boundary. Boundary node movement is

controlled by the specified maximum perimeter element aspect ratio.

Enter the maximum perimeter element aspect ratio as shown in the following image:


If the model already contains collectors 2DBLMeshand 2DCoreMesh, then a pop-up message will ask

you if you want to delete components 2DBLMeshand 2DCoreMeshbefore mesh creation or if you wantto add newly created elements to the same collectors. Most of the time you will want to clear the

existing mesh: click Yes. In some special cases you may want to keep them.

When this task is finished, two collectors 2DBLMeshand 2DCoreMeshare updated with new elements

as shown in the following image:

3. You can check the elements aspect ratio by using the shortcut key F10 and selecting the 2-dpage.


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When the perimeter has sharp angles as shown in the following image, triangular elements are added to

the boundary mesh to achieve a smoother transition of element sizes, and mesh smoothing also

contributes to increase the mesh quality.


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Also note that the automatic mesh generator performs a collision detection and avoids boundary layer

interference by reducing the boundary layer thickness, as shown in the following inset:

Step 7: Use a distributed boundary layer thickness to generate a boundary layer


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and core

The boundary layer type mesh generated in this tutorial was generated with uniform thickness. This is OK for

a model like this manifold as long as the total boundary layer thickness does not lead to collision or

interference that can occur when the sum of the BL thickness is close to or larger than the distanceseparating opposite walls. When such collision or interference occurs you have the following options:

Decrease the global boundary layer thickness (throughout / for all the BL edges).

Decrease locally the boundary layer thickness (BL edges around critical zones only).

Decrease locally the boundary layer thickness.

1. In the 2D Boundary Layer Meshwindow, click Rejectto remove the created mesh.

Collectors 2DBLMeshand 2DCoreMeshwill be deleted.

2. Click Closeto close the pop-up window.

Create new components (empty) to place the PLOTEL elements at critical zone (area whereboundary layer elements may lead to collision).

3. Open the Model Browser.

4. Click BCs > Comp onents > Single.

5. Enter name as wall_critical.

6. Click Create and then Close.


8. Select the boundary edges (PLOTEL) around the area where boundary layer elements may lead to

collision. Refer to the following image for element selection.

9. Set the dest group/dest com pon entswitch to dest comp onent =and select the destination collectoras wall_cr it ical.

10. Click moveto move the selected PLOTEL elements to the destination collector.


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11. Click Mesh > Surface Mesh 2D > 2D Mesh wi th BL .

12. In the 2D Native BL (planar)tab, click A dd col lector.

13. In the panel area, click comps.

14. Select the component wall_critical.

15. Click select.

16. Click proceed.

The component wall_criticalhas been added to the component list.

17. Set 1st First Layer Thick nessof component wall_criticalto 0.4.


When this task is finished, two collectors are automatically created: 2DBLMeshand 2DCoreMesh.

19. Now you can zoom in around component wall_criticaland notice how boundary layer interference has

been avoided by reducing the total boundary layer thickness as shown in the following image:


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Summary

In this tutorial you generated 2-D meshes with boundary layers on a complex cross section. You obtained a

high quality mesh by allowing boundary node insertion and movement. Engineering Solutions automatically

cuts back the number of layers when boundary layer collision occurs, thus producing a consistent mesh

even in narrow areas. In narrow passages you can also reduce the total boundary layer thickness by starting

with a smaller first layer thickness and/or a smaller growth rate.


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CFD-1400: Wind Tunnel Mesh

In this tutorial you will generate a wind tunnel type mesh for external CFD analysis. The mesh consists of a

Cartesian hexa-mesh for the far field, and a hybrid grid (tetras with boundary layers) in the vicinity of the

object.

The tutorial includes the following steps:

Setting the user profile

Opening the model file to be used

Using the wind tunnel functionality

Surface meshing

Volume meshing using the CFD Tetrameshpanel

Organizing the model and preparation for CFD export

Export for Fluent

Exercise


1. From the menu bar, select Preferences, then User Profi les.

2. For Application, select Engineering Solut ion sand click the CFDradio button.

3. Click OK.


1. From the toolbar, click the Open M odel icon .

2. Select the airplane.hmfile from the directory \tutorials\es\cfd .

3. Click Opento load the file.


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Step 3: Use the Wind Tun nel Mesh tool

1. Click Mesh > Vol um e Mesh 3D > Win d Tunnel.

The Wind-Tunneltab opens, displaying instructions for using this tool.

2. Enter values for your model as shown in the following image:

3. Click Generate.

A pop-up message will display the estimated number of hexahedral elements that will be created with

the specified minimum hex cell size.

4. Click Yeson the pop-up message.

The Wind Tunnel Meshtool generates hexa, pyramids and shell elements and groups them into several

collectors.


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You may need to rotate the model to obtain this view .

Step 4: Generate a shell mesh on the airplane

1. In the ModelBrowser, expand Component, right-click plane, and select Isolate.

2. Click Mesh > S urface Mesh 2D > Au tomesh.

This automatically loads the surfacedeviationsubpanel.

3. With surfsselected in the toggle, hold SHIFT and drag a box around the entire visible airplane geometry.

You may need to resize the display first.

4. For element size =, enter 10.

5. For growth rate=, enter 1.2.

6. For min elem size =, enter 2.

7.For max deviation=, enter 0.1.

8. For max feature angle =, enter 15.

9. Set mesh type:to tr ias.

10. Ensure toggles are set to elems to surf compand first order.

11. Click mesh.


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A message on the status bar indicates the number of elements created.

Step 5: Mesh the box symcomponent with an element size of 20

1. In the Model Browser, show the elements and geometry for box_sym.

2. In the Automesh panel, click the size and biassubpanel.

3. With the surfstoggle active, click any visible part of the box to select it.

4. For element size =, enter 20 and set the mesh type to tr ias.

5. For map:, activate the checkboxes for sizeand skew.

6. Click mesh.

The component is meshed. A message on the status bar indicates the number of elements created.

7. Click returntwice to return to the main menu.


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Step 6: Equivalence nodes in box_sym

1. In the Model Browser, right-click on the component sympand select Show.

2. Click BCs > Check > Edge.

3. Click the yellow compsbutton and select the components box_symand symp.

4. For tolerance =, enter 0.1.

5. Click preview equi v.

A message in the status bar indicates the number of nodes found.

6. Click equivalence.

The nodes are equivalenced.


Step 7: Create new componentbox_groun d

1. Click BCs > Comp onents > Single.

2. In the Name:field, enter box_ground.

3. Click Colorand select magenta.

4. Click Create.

The new collector has now been created.


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5. Close the dialog.

Step 8: Generate a surface and a tria mesh on the bottom of the box

1. In the Model Browser, turn off the element display for sympand turn on the display for ground.

2. Click Mesh > S urface Mesh 2D > Surface/Mesh > Spl ine.

3. Set the selector toggle to nodes.

4. Click the nodes selector to open the extended entity selection menu and pick by p ath.

5. Set the second toggle to surface on ly.

6. Pick the nodes by path on the perimeter of the box bottom, as in the following image:

7. Click create.

8. Click return.


10. Select the size and biassubpanel, ensure the selector is set to surfs and the element sizefield is set

to 20.

11. In the graphics area, click the box_groundsurface.

12. Click mesh.

A message on the status bar will indicate the number of elements created.

13. Click returntwice to return to the main menu.

Step 9: Equivalence nodes to achieve a closed volume

1. Click BCs > Check > Ed ge.


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2. Click the yellow compsbutton and select the components plane, box_sym, ground,

trias_hexas_pyras, and box_ground.

3. Set the tolerancefield to 0.1.

4. Click preview equi v.

5. Click equivalence.

6. Click return.

7. In the Model Browser, turn off the display of ground, and turn on the element display of

trias_hexas_pyras.

8. Return to the Edgespanel.

9. Hold SHIFT and drag a box around all the visible components to select them all.


A message on the status bar indicates that no edges were found.

11. Select the components again and click preview equi v.

A message on the status bar indicates that 0 nodes were found. This ensures that the volume is

enclosed, which is necessary for the following tetra meshing step.

12. Click return.

Step 10: Mesh the closed volume

1. Click Mesh > Vo lum e Mesh 3D > CFD tetram esh.

2. Under the With boundary layer (fixed) header, click the compsselector and select the component


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plane.

3. Under the W/o boundary layer (fixed)header, click the compsselector and select the components

box_sym, box_ground,and trias_hexas_pyras.

4. Click to the BL Parameterssubpanel,

5. For number of layers=, enter 3.

6. For first layer thickness=, enter 0.7.

7. On the Tetramesh Parameterssubpanel, set the toggle to interpolate.

8. Click mesh.

The mesh may take a few minutes. When the mesh is complete, a message in the status bar will

indicate the number of nodes and elements created.

Note that two new components, CFD_tetramesh_coreand CFD_boundary_layer, appear in the Model

Browser.

9. Click return.

Step 11: Inspect the mesh

1. Click Mesh > Check > Hidden Li nes. In the panel, deactivate the clip boundary elementscheckbox.

2. Click show plo tand then check and then uncheck the xy plane, yz plane and xz plane checkboxes

to display the model in different views.


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3. Rotate and inspect the mesh from the side of the model.

4. Click and hold one of the corners of the model. While keeping the mouse button down, drag the corner of

the model forth and back to sweep the cutting plane.

5. Click return.

Step 12: Organize faces

1. In the Model Browser, turn off the display for plane, box_sym, trias_hexas_pyras, and box_ground

so that only CFD_tetramesh_coreand CFD_boundary_layerare visible.

2. Click BCs > Faces.

3. Hold SHIFT and drag a box around the visible components to select them.

4. Click f ind faces.

Note that a new component named ^facesappears in the Model Browser.

5. Click return.


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6. In the Model Browser, turn off the display of the elements of CFD_tetramesh_coreand

CFD_boundary_layer.


8. Click elems and select on plane.

9. Pick three nodes on the ^facescomponent, on the face that intersects the airplane model.

A good way to determine which area to select is to isolate the display of the box_symgeometry. This

will show you the face to focus on. Turn the display of the ^facescomponent back on, and select your

three nodes.

10. Click select enti ties.

11. Click dest compon ent =and select symp.

12. Click move.

13. Click elems >> on pl ane.

14. Pick three nodes on the bottom of the ^facescomponent.

A good way to determine which area to select is to isolate the display of the box_groundgeometry.

This will show you the face to focus on. Turn the display of the ^facescomponent back on, and select

your three nodes.


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15. Click select enti ties.

16. Click dest compon ent =and select ground.

17. Click move.


Step 13: Delete collectors

1. In the Model Browser, right-click the component ^faces, and select Delete.

2. In the pop-up dialog, click Yesto confirm the deletion.

3. In the Model Browser, turn on the display of CFD_tetramesh_coreand CFD_boundary layer.

4. Press the CTRL key and select edges_xzand edges_xyin the Model Browser.

5. Right-click and select Delete.

6. In the pop-up dialog, click Yesto confirm the deletion.

7. In the same way, also delete trias_hexas_pyras,box_sym andbox_ground.

Step 14: Organize components



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2. Click elems and selectby col l ector.

3. Select CFD_tetramesh_coreand CFD boundary_layer.

4. Click select.

5. Click dest compon ent =and select fluid_hex.

6. Click move.

When the move is complete, nothing should be visible in the graphic area.

7. Click return.

Step 15: Use the Model Browser to rename and delete components

1. In the Model Browser, display elements for fluid_hex.

2. Right-click fluid_hexin the Model Browserand select Rename.

3. Enter the new name as fluid.

4. Select CFD_tetramesh_coreand CFDboundary_layerand delete them using the process described in

Step 14.

5. Right-click Componentand select Showto show all remaining components in the graphic area.

Step 16: Export the file as .cas.

1. Select Expo rt Solver Deck .

2. Ensure that CFDis selected for the File Type, and pick f luentfor the Solver Type.

3. Use the Fi lefield to navigate to the destination folder and enter the name wind_tunnel_mesh.

4. Click Expor t.

A pop-up dialog appears. After reading the dialog, click Yes.


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5. In the pop-up dialog that appears, you are asked whether to reuse the setup from an existing Fluent file.

Since youjust generated the grid and dont have a set up file (*.cas), click No.

It may take a few minutes for the file to be created.

6. When the file creation is complete, a pop-up window appears. Click OK.


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CFD-1500: Hexcore Meshing with Boundary Layer

In this tutorial you will learn how to generate a hexcore mesh with a boundary layer. Included are the

following steps:

Tria surface meshing

Boundary layer generation

Generation of the hexcore mesh, pyramid elements and the tetra mesh

Preparation of the model for the export

Exercise


1. From the menu bar, select Preferences, then User Profi les.

2. For Application, select Engineering Solut ion sand click the CFDradio button.

3. Click OK.


1. From the toolbar, click the Open M odel icon .

2. Select the ujoint_cfd.hmfile from the directory \tutorials\es\cfd .



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Step 3: Generate a mesh on the surface

1. In the ModelBrowser, expand Component, right-click on itand select Show.


3. Click the size and biassubpanel.

4. Set the element size =field to 5.0.

5. Click the mesh typetoggle to tr ias.

6. Ensure that both the size and skewcheckboxes are activated.

7. Ensure toggles are set to elems to surf compand first order.

8. Click the yellow surfsbutton and selected al l.

9. Click mesh.

A message on the status bar indicates the number of elements created.

10. Click return twice to close the panels.

Step 4: Mesh the hex-core

1. Click Mesh > V olum e Mesh 3D > Hex-core.


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2. Enter the parameters as shown in the image below:

3. Checking the box for Generate exterior tetrahedral meshand Boundary Layermakes the bottom


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part of the tab editable. Enter the Number of layers as 3, the First layer thicknessas 0.4and the

Growth rate as 1.2.

4. Under the header With boundary layer, click the Componentsbutton and select the component wall.

5. Under the header W/o boundary layer, click the Componentsbutton and select inflowand outflow.

6. Click Generatejust above the Report area. After the meshing finishes, a message appears stating that

additional components have been created.

7. Check the Model Browserto see all the new components created.

8. Press F5to open the Maskpanel. While holding the shift key down, draw a box around roughly half of

the model, and click mask. This will display the inside of the model.


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Step 6: Prepare the model for export

1. In the Model Browser, right-click on Component and select Create.

2. Enter the name as fluidand click Create.

3. Right-click on Component again select Showto remove the masking effect.

4. From the Viewmenu, select the Mask Browser.

5. Display only the volume elements by clicking on the "1" in the row for 3D elements, as shown below:


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6. Click Mesh >Organize.


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7. Click elemsand select displayed.

8. Click dest compon ent = and select the f lu idcomponent.

9. Click move, and then click return.

10. In the Mask Browser, set only the 2D elements to display.

11. Click Mesh> Delete> Elements. Click the yellow elemsbutton and select displayed.

12. Click delete entity. This deletes all 2D elements from the model.

13. While still in the Deletepanel, click the toggle and switch from elemsto comps. Click compsand

select the components that are now unused:CFD_boundary_layer

hexcore

pyramids

faces_pyra_hex

tetras_exterior

14. Click delete enti ty and click return.

15. In the Model Browser, right-click on Componentand select Showto display the remaining

components. Only volume elements are now available in the model.

16. Click BC >Faces.

17. Click the compsbutton and select the fluidcomponent.

18. Enter the toleranceas 0.010and select f ind faces. Click returnto close the panel.



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20. Click elemsand select the elements on the inlet.

21. Click dest comp onent = and select the inflowcomponent. Click move.

22. Click elemsagain and select the elements on the outlet.

23. Click dest comp onent = and select the outflowcomponent. Click move.

24. Click elemsagain, select by col l ectorand select ^faces.

25. In the dest comp onent =field, select walland click move. This will move the remaining elements in

the ^facescomponent into the wallcomponent.

26. In the Model Browser, delete the ^facescomponent.

27. Display all the components and export the model to the CFD solver of your choice.


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CFD-1600: Using Distributed Thickness for Varying Boundary LayerThickness

In this tutorial you will learn how to

Generate a structured quad surface mesh

Adjust the boundary layer thickness manually

Generate a hybrid grid (tetramesh with boundary layer)

Exportthe model for a CFD solver of your choice

Exercise

Step 1: Load the CFD user profile1. From the menu bar, select Preferences >User Profil es.

2. In the Applicationfield, select Engineering Solut ions.

3. Select the CFDradio button.

4. Click OK.


1. From the toolbar, click the Open M odel icon .2. Select the wing.hmfile from the directory \tutorials\es\cfd .



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4. In the Model Browser, click on Componentand expand the folder, then right-click on boxand select

Hide.

5. Right-click on planeand select Show.

Step 3: Generate a mesh on the surface


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