Project 1 : CFD Meshing for Tesla Cyber Truck

Aim

For the given model of Tesla Cyber Truck, check and solve all geometrical errors and Assign appropriate PIDs. Perform meshing with the suitable Target length and element Quality criteria.

Procedure

• After importing model delete half model and ‘topo’ is applied on it to join the single cons into double and triple con.
• Single cons and triple cons are identified and Topo-cleanup is done to patch the open surface and delete unwanted surface.
• Topo cleanup for model is done by deleting unnecessary surfaces from model to remove triple cons, delete un-wanted hot points, and single cons are removed by patching the surfaces using New-Coons/Fitted options
• Topo cleanup of door handle includes removing triple cons by deleting the unwanted surfaces.
• Geometric checks are performed to have no single cons present in the model and possible triple cons are removed by deleting it using universal delete option. The final Topo cleanup is shown in figure 1 & 2.

Figure 1

Figure 2

• PID’s are assigned using the PID manager for all parts in the body as showm in figure 3.
  

Figure 3

• Before creating surface mesh the cons and small edges that have length less than minimum mesh length are identified by measuring the distance between cons and solved using ‘cut’ option in order to avoid mesh failing the mesh criteria at this small surfaces.

Surface Mesh

Target lengths for the different parts of a model are as follow:

1. Body - 5 mm (min: 1 mm , max: 6 mm)
2. Rims and Tyres - 3 mm (min: 1mm , max: 4 mm)
3. Window - 3 mm (min: 1 mm , max: 4 mm)
4. Wind-shield – 3 mm (min: 1 mm , max: 4 mm)

Individual elements are meshed with respective mesh length with minimum and maximum length.

Surface meshing for tires: Tires are isolated and given a mesh length of 3 mm with minimum and maximum length of 1 mm and 4 mm with triangular elements. Other mesh criteria’s are as shown in figure 4.

Figure 4

• The mesh improvement can be done by using options like Reconstruct, Split, Smooth, Move the grid.
• Once the off element’s number boils down to 0 then meshing is done successfully, and Similar method is used for other PID’s. The Final Mesh on the half part of Truck is shown in the figure 5.
  

Figure 5

• Symmetry need to be performed on the other half of car in which the all the components with mesh are copied directly to the other side using Transform option from the top side option list. The full mesh model of a car is as shown in figure 6.

Figure 6

Wind Tunnel

• The wind tunnel dimensions are , if x is the length of Truck (5660 mm) then

Front of wind tunnel is 4X (22700 mm) from the truck

Rear of wind tunnel is 6X (33960 mm) from the truck

Top of wind tunnel is 3X (16980 mm) from the truck

Side walls of wind tunnel are at X from the side portion of truck

• Bottom of wind tunnel is in close proximity of wheels
• Points are created by using ‘Relative option’ in points of Topo Deck.

Topo Deck- points- relative –points- select points. After the points are created join these points from bottom plane by ‘create curves’

• Once the curves are created for top and bottom then create a surface with help of ‘New’ option in ‘faces’

Topo – Faces- New-Fitted-will open PID manager window- create new PID-double click on it to create surface on it.

• As the analysis of what happens over the surfaces of car is of importance so the bottom of wind tunnel should have good resolution as compared to top portion as it relatively at larger distance than bottom. So mesh length of 40 is taken at bottom and 200 for top portion.
• As the front and rear of car are connected with the top and bottom surfaces then the mesh length for this surfaces should vary from 40 to 200 from bottom to top portion. This gradual variation can be achieved using ‘Spacing’ option from the perimeters section of Mesh deck.

Perimeters-Spacing –Geometric – factor of 1.1 and d-min of 40, d-limit of 200 successful application of this will be indicated by upward pointing arrows.

• Mesh is generated by applying Spot mesh for individual surfaces. The final surface mesh for wind tunnel is shown in figure 7.

Figure 7

Conclusion

All parts were surface meshed including wind tunnel surface.

Link

Tunnel: https://drive.google.com/file/d/11NMAC7FpJwtKG9rl50G0kJ1QK2jqh3t4/view?usp=sharing