1. Introduction

The main objective of the challenge is to perform a Topology Cleanup and mesh the given geometry of a Tesla Cybertruck with desired mesh length elements to understand the variation in the mesh lengths and further a Wind tunnel is to be created around the geometry which is to be forwarded for physics simulations.

Following are the basic tools that will be used in the geometry to get the required output.

1. Or – To isolate a face of the geometry.
2. And – To show the neighbouring face of the geometry.
3. Not – to hide the selected faces of the geometry.
4. !Not – To isolate a face of the geometry.
5. All – To show all the faces of the geometry.
6. Invert – To show the opposite faces of an isolated face of the geometry.
7. Lock – To lock the existing faces of the geometry.
8. PID – To differentiate different regions of the geometry using colours and region name.

2. Clean-up of Geometry

For any geometry before meshing, it is necessary to be cleaned up with its topology in-order to obtain a good surface mesh used for analysis. Before proceeding with the Clean-up, it can be observed that the entire geometry shows Single Cons. This can be corrected using the TOPO tool from the FACES section. The corrected representation is as below.

2.1 Body

1. In this geometry, there are observed to be a lot of missing surfaces which can be created using NEW tool in the FACES section with COONS option as represented below.
   
   
   
   
2. At the rear of the body, the missing surface is created using FITTED option in the NEW tool of FACES section. This option is used due to unevenness in the surfaces attaching Rear Light and the Body results in creation of unwanted cuts in the surface. The representation of the same is as below.
   
   
   
   
3. After the creation of the missing surfaces, it can be observed that there are unwanted Hot Points and uneven surfaces are present. These unwanted surfaces and hot points are to be deleted and new surfaces are created using NEW tool in the FACES section with FITTED option to avoid creation of unwanted Cuts as represented below for both before and after the clean-up is executed.
   
   
   
   
   
   
   
4. The geometry is further checked for cuts which could possibly creates an issue with the mesh by creating some violating elements. So these cuts are identified and are deleted by right-clicking these cuts using CUT option in the FACES section. It is as represented below.
   
   

2.2 Rims & Tyres

1. Firstly, the missing Faces are to be created to get the Double Cons which can be done using the FITTED option in the NEW tool of FACES section as represented below. FITTED is used as using COONS option gives an unwanted cut in the surface.
   
   
   
   
   
   
2. The missing Faces are to be created to get the Double Cons which can be done using the FITTED option in the NEW tool of FACES section as represented below.
   
   
   
   
3. Coming to the Unwanted surfaces, these are deleted and in their place, a new surface is created using the FITTED option in the NEW Tool of FACES section. The representation of it is as below.
   
   
   
   
4. Before proceeding to meshing, the geometry is to be checked for unwanted cuts on its surface which possibly creates an issue with the mesh by creating some violating elements. So these cuts are identified and are deleted by right-clicking these cuts using CUT option in the FACES section. For some cases, PARAMETRICAL of 0.38 from HOT POINTS section is used to create a Hotpoint at a required spot and cut the unwanted length as represented below.
   
   

2.3 Front & Rear Lights

1. For the Front lights, it can be observed that there are unwanted Hot Points and uneven surfaces are present. These unwanted surfaces and hot points are to be deleted and new surfaces are created using NEW tool in the FACES section with FITTED option to avoid creation of unwanted Cuts as represented below.
   
   
   
   
   
   
2. For the Rear lights, these unwanted surfaces and hot points are to be deleted and new surfaces are created using NEW tool in the FACES section with FITTED option to avoid creation of unwanted Cuts as represented below.
   
   
   
   

3. PID Assignment

It can be observed from the Properties section is that there are a lot of PIDs assigned for all the surfaces which needs to be assigned together which will be helpful to assign the different Mesh lengths in further sections.

1. A right click in the properties window and clicking on the NEW option creates new PID which can be renamed as per the requirement.
2. Based on the new PIDs created and named according to the parts, right clicking on the PID and clicking on the Apply will help in getting the selected PIDs to be applied to the new PID as represented below.
   
   
   
   
3. After the creation of new PIDs, all the old PIDs can be deleted by using the Compress tool as represented below.
   
   
   
   
4. All the new PIDs can be observed in the Properties Window after deletion of the unwanted PIDs as represented below.
   
   
   
   
5. In the coming sections, after the creation of the Wind Tunnel, new PIDs will be added using the same procedure.

4. Meshing the geometry

Meshing different parts of the geometry as per there minimum lengths which could be determined using the MEASURE tool. Based on these minimum values and Maximum values obtained from taking the measurements, Target Length values are to be setup. The Target Length values are as mentioned below.

1. Body - 3 mm
2. Lights - 4 mm
3. Windows - 3 mm
4. Rims and Tyres - 2 mm

The Meshing of different parts of the body will be explained as individually.

4.1 Body

1. Quality Criteria and Mesh Parameters are setup using these values.
   Target Length – 3 mm
   Minimum Target Length – 2 mm
   Maximum Target Length – 4 mm
   
   
   
   
2. For the selection of Perimeter edges, apart from the Lights at the front and rear, rest are selected. This can be seen in the representation below.
   
   
   
   
   
   
   
   
3. LENGTH option is used to assign the target lengths to the geometry for both Perimeter and Macros with the same Target Length.
   
   
   
   
4. The geometry is to be meshed by using the SPOT MESH option and selecting the VISIBLE it to get the Mesh for the geometry.
5. Now the HIDDEN tool is used to check for the Off Elements which can be resolved using a RECONSTRUCT option in the SHELL MESH Section.
   
   
   
   
   
   
   
   
   
   
6. If this option doesn’t seem to resolve the issues, the below options are used in order to get the Off elements resolved. It is as mentioned below like SMOOTH, SPLIT and MOVE.
   SPLIT – This option helps in splitting the edges of an element resulting in formation of more elements.
   MOVE – The MOVE option is used to manually adjust the nodes of the element.

4.2 Rims & Tyres

1. Quality Criteria and Mesh Parameters are setup using these values.
   Target Length – 2 mm
   Minimum Target Length – 1 mm
   Maximum Target Length – 3 mm
   
   
   
   
2. LENGTH option is used to assign the target lengths to the geometry for both Perimeter and Macros with the same Target Length.
   
   
   
   
3. The geometry is to be meshed by using the SPOT MESH option and selecting the VISIBLE it to get the Mesh for the geometry.
4. Now the HIDDEN tool is used to check for the Off Elements which can be resolved using a RECONSTRUCT option in the SHELL MESH Section.
   
   
   
   
   
   
5. If this option doesn’t seem to resolve the issues, the below options are used in order to get the Off elements resolved. It is as mentioned below like SMOOTH, SPLIT and MOVE.
   SPLIT – This option helps in splitting the edges of an element resulting in formation of more elements.
   MOVE – The MOVE option is used to manually adjust the nodes of the element.

4.3 Windows

1. Quality Criteria and Mesh Parameters are setup using these values.
   Target Length – 3 mm
   Minimum Target Length – 2 mm
   Maximum Target Length – 4 mm
   
   
   
   
2. LENGTH option is used to assign the target lengths to the geometry for both Perimeter and Macros with the same Target Length.
   
   
   
   
3. The geometry is to be meshed by using the SPOT MESH option and selecting the VISIBLE it to get the Mesh for the geometry.
4. Now the HIDDEN tool is used to check for the Off Elements which can be resolved using a RECONSTRUCT option in the SHELL MESH Section.
   
   
   
   
   
   
5. If this option doesn’t seem to resolve the issues, the below options are used in order to get the Off elements resolved. It is as mentioned below like SMOOTH, SPLIT and MOVE.
   SPLIT – This option helps in splitting the edges of an element resulting in formation of more elements.
   MOVE – The MOVE option is used to manually adjust the nodes of the element.

4.4 Lights

1. Quality Criteria and Mesh Parameters are setup using these values.
   Target Length – 4 mm
   Minimum Target Length – 3 mm
   Maximum Target Length – 5 mm
   
   
   
   
2. LENGTH option is used to assign the target lengths to the geometry for both Perimeter and Macros with the same Target Length.
   
   
   
   
3. The geometry is to be meshed by using the SPOT MESH option and selecting the VISIBLE it to get the Mesh for the geometry.
4. Now the HIDDEN tool is used to check for the Off Elements which can be resolved using a RECONSTRUCT option in the SHELL MESH Section.
   
   
   
   
   
   
   
   
5. If this option doesn’t seem to resolve the issues, the below options are used in order to get the Off elements resolved. It is as mentioned below like SMOOTH, SPLIT and MOVE.
   SPLIT – This option helps in splitting the edges of an element resulting in formation of more elements.
   MOVE – The MOVE option is used to manually adjust the nodes of the element.

5. Wind Tunnel Creation and Meshing

After the creation of Mesh for all the PID regions, it is necessary to check for any remaining errors which needs to be avoided in-order to avoid its interference in the Surface and Volumetric Mesh. This can be checked by using Geometry Checks and made sure that there are no errors occuring.



With this, Wind Tunnel Creation and its Meshing process can be initiated.

5.1 Wind Tunnel Creation

1. To create the Wind Tunnel around the geometry, it is necessary to create boundary points first with reference to the geometry. To get these boundary points, RELATIVE option is used from the POINTS section. This option helps in creating a point relative to a selected point in any of the X, Y or Z direction.
   
   
2. Upon creation of the first Point as per their respective formulae, the remaining Points are to be created realtive to the first point as rerpresented below.
   Front Point - 2644 + 4(x) = 2644 + 4(5906) = 26268.
   Rear Point - 3409 + 4(x) = 3409 + 4(5906) = 38845
   Top Point - 2301 + 3(x) = 2301 + 3(5906) = 19542
   Side Point - 3 x Width of Car = 3 x 2080 = 6240
   
   
   
   
   
   
   
   
   
   
3. After creating these reference points, a curve is created joining these points by using the CREATE option in CURVE section as below.
4. Upon creating these curves, with its reference, a face is created which will further help in creating other faces of the wind tunnel.
5. To create the top face of the wind tunnel, the bottom face created can be utilised for it. This can be done by using the OFFSET option from the FACES section. This can be done by assigning an Offset Value of 4275 mm.
   
   
   
   
6. The other remaining faces can be created using NEW option in the FACES section with reference to the created Base and Top faces as below.
   
   
   
   
7. After the creation of these faces for the Wind Tunnel, their respective PIDs are also created using the steps mentioned in Section 3. The updated properties window is as represented below.
   
   

5.2 Wind Tunnel Meshing

1. 1. As the Wind Tunnel is created, the next step is to Mesh the Wind Tunnel Surface which further can be utilised for Volumetric Mesh. but in this it can also be observed that the Mesh will become Coarse when the mesh moves away from the main geometry which is expected.

   2. For this particular mesh, the quality criteria of Maximum and Minimum lengths cannot be used. For this, the Mesh Taget lengths mentioned below can be assigned in the Mesh Parameters pop-up window forr minimum and maximum being + or - 5 of the Target Mesh Length (These values have been utilised considering the computational power).
      Top surface = 150 mm.
      Bottom surface = 50 mm.
      
      
      
      

   3. Since the Mesh Lengths for Top and Base faces are different, for the Front, Rear and Side faces, variable mesh length is to be assigned which can be done by using SPACING option from the PERIMETERS section. Required vertical edges of the Wind Tunnel Geometry is to be selected as represented below.
      
      
      

   4. Meshing of these unmeshed surfaces is to be done indeviually by using "local" for Target Length since the mesh to be created is variable in this case. The below representation shows the created Surface Mesh for the Wind Tunnel Structure.
      
      

   5. Point to be noted in here is that the Volumetric Mesh has not been performed in this Challenge as it considerably takes longer to complete the mesh. So the Model is being submitted after performing a surface

6. Conclusion

The objective of performing a Topology Clean-up and meshing the geometry of a Tesla Cybertruck with their respective Mesh Target Lengths has been performed and further a Wind tunnel has been created around the geometry which can now be forwarded for physics simulations.

Point to be noted in here is that the Volumetric Mesh has not been performed in this Challenge as it considerably takes longer to complete the mesh. So the Model is being submitted after performing a surface Mesh.

To support the output, below is the Model Link to the output geometry.

Model Link: Project 1: CFD Meshing for Tesla Cyber Truck