Project 1 : CFD Meshing for Tesla Cyber Truck

AIM: To check and solve all geometrical errors and meshing with the suitable Target length and element Quality criteria.

TOOLS USED:

Classic TOPO:

1. Checks: It is used to check the errors in the model.

• Geometry: It is useful to find errors in the geometry.

2. Hot Points:

• project: It projects the points in the selected cons or faces.

3. CONS:

• Fill hole: It fills the holes and openings.
• Release: It releases the topology of selected CONS.

4. Faces:

• New: It is useful to create a new face anywhere in the geometry.
• Delete: If any unwanted part is created it will remove it.
• TOPO: It merges the CONS.
• Intersect: Intersects the two different faces.
• Cut: It cut the faces from cons and nodes.
• Extend: It is used to extend the face to desired con.
• Offset: It creates face perpendicular to the original one at desired distance.

5. Curves:

• Create: It creates the 3D curves.
• Delete: It delete 3D curves.

6. Points:

• Relative: It defines 3D curves by a relative position.

7. ENT: It can select any entity one by one.
8. PID: It can select one by one or with the box selection.
9. Not: It disappears the visible entities.
10. All: Bring back all the entities to the current window.
11. Compress: It compress the unused entities.
12. Auxiliaries:

• Fine: It increase or decrease the resolution of selected CONS or curves.

13. Loop: It selects the cons which are looped in.
14. Lock: Lock the current entities visible.
15. Views Manager.
16. Transform: Copy or remove required entities.

Classic Mesh:

1. Perimeters:

• Length: It is defined to mention the distance of the nodes.
• Spacing: It controls spacing between the nodes of a assigned con.

2. Macros:

• Move: It moves the nodes from the face.
• Paste: It pastes the nodes.

3. Mesh Generation:

• Spot mesh: It is the tool to mesh the geometry by nodes on the surface.
• Erase: It removes the Mesh.

4. Shell Mesh:

• Reconstruct: It improves the quality of the mesh after applying.

5. Mesh parameters: For improvement of mesh generation.
6. Quality criteria: For the quality presentation of the geometry.
7. PIDs: Property list for specifications of properties and boundary condition.

Volumetric Mesh:

1. Volumes:

• Define: Definition of volume entities.

PROCEDURE:

1. Open the model in the ANSA.
2. To make the model visible with the faces use the ‘shadow tool’ present in the bottom of the window.
3. As we need a error-free geometry we split the car in half for easy work. Do this if you have symmetrical parts.
4. By using “transform>entities>symmetry” you can split the model.
5. Then go for the “checks>geometry” and check how many and where are the errors and then execute.
6. To create a new face there are different methods to use, by using the tool “faces>new>existing surface.”
7. For checking the overlapped surface, you can use “Faces>TOPO.”
8. Delete the overlapped surface by using universal delete option by selecting the surface which you want to delete.
9. If any extended surface is located first intersect by using “faces> intersect” tool and delete the surface once it forms a con.
10. If you use release tool “Cons>Release” it will separate triple con into three different single cons.
11. If you do ‘TOPO’ from ‘faces’ it will do the opposite of the release, it will merge the cons to form a double con.
12. If you don’t want a face or a line in the model, you can remove it by using “TOPO>Faces>Delete.”
13. Topology cleanup is done for the car.
14. After the topology cleanup assign the PIDs for parts by using PIDs properties. And by using tools from feature selection: ENT & PIDs>PID/PID region.
15. After completion of Topology cleanup let us move to the surface mesh.
16. Whenever you start with the mesh first step should be giving its length by using “Classic Mesh>perimeters>length.”
17. In the length option set the Perimeters and Macros length as per the requirements.
18. After mentioning the length, give the target length and element type as ‘tria’ in the Mesh parameters and check the quality criteria and change the min and max length.
19. After giving the lengths mesh the components individually with the defined lengths.
20. Every component has different criteria, so it is changed accordingly.
21. After giving the parameters deploy the Mesh by using tool “Mesh generation>Spot mesh.”
22. Doing mesh for individual parts give the fine mesh but as you turn on the Hidden option you can check the violating elements.
23. To clear those use “Shell mesh>reconstruct” it will clear as much as possible and remaining you use “Grids>Move” to move the elements to have an error less surface.
24. After the surface mesh is done, do the symmetry by using transform.
25. After performing symmetry create the Wind Tunnel.
26. For creating the face, you need points, so to get points on the right place you can use “points>relative>nodes” by selecting the middle point of the car create the point as distance of 500mm.
27. After creating required points use “curves>create” option to create lines the use new option to create the face after creating that use “Faces>offset” option to create that face perpendicular to the original one.
28. The dimensions are as follows:
• Height: 7800mm
• Length: 59830mm
• Width: 9008mm
29. After creating the faces with the calculated dimensions proceed for the wind tunnel surface mesh.
30. Every face has its own mesh criteria, for getting fine mesh give the mesh parameters as:

• Top Surface:
  • Target length: 300mm
  • Minimum length: 280mm
  • Maximum length: 320mm
• Base Surface:
  • Target length: 60mm
  • Minimum length: 55mm
  • Maximum length: 65mm

31. For Side, Front and Rear surfaces target lengths should be different for doing that ypu can use “perimeters>spacing” in the mesh deck, give the parameters as:

• Biasing: Geometric
• Factor: 1.1
• Dstart: 60mm
• Dlimit: 300mm

32. Do the mesh as you can see the mesh varies from 60mm to 300mm.

33. As you complete the go to the V.Mesh.

34. Volumetric mesh is a kind of 3D element mesh.

35. After entering the V.Mesh your first task is to define the model by using (“V.Mesh>Volume>Define.”)

36. In that you can choose it as a visible model or whole database as per your requirements.

37. Choose the whole database and click ‘ok’.

38. It will show you the volume list, by default it will detect the volumes.

39. Volumes are nothing but ANSAs closed geometry, which is closed in the TOPO mode.

40. Few volumes are useful and other you can delete if not necessary.

41. We will be only meshing the volume that occupied by parent geometry thickness.

42. As you can see the volumes there will be a particular volume which is connected with the wind tunnel then you can proceed further for V.Mesh.

FIG 1. Before the TOPO cleanup

FIG 2. After the TOPO cleanup

FIG 3. Symmetry done

FIG 4. Showing the results of mesh

FIG 5. Mesh done with Zero Off elements

FIG 6. Wind Tunnel mesh done

FIG 7. Showing the connection of car and wind tunnel in one volume

RESULT:

• The main model is cleaned up and fully refined
• Mesh done successfully for the car with the different parameters and criteria.
• Wind tunnel created and meshed successfully.

ERROR:

• While doing V.Mesh, the define and mesh option is not responding and running it multiple times the software is crashing.

CONCLUSION:

The given Car model and wind tunnel has been cleaned up and with the suitable target lengths, quality criteria and element type it is successfully meshed.

GEOMETRY: https://drive.google.com/file/d/1cqzk5PwRYk7SkOqobwJ-BT-rLke4kOX1/view?usp=sharing