Project 1 : CFD Meshing for Tesla Cyber Truck

CFD Meshing for Tesla Cyber Truck

AIM

The Cyber Truck car model was created by Tesla Company in 2019, being well known due to its weird shape can be considered as a highly aerodynamic shape. This car is shown in the next picture and as can be seen below, it is a simple car body with a large trunk and big wheels, however, besides its highly aerodynamic shape, Tesla used metal materials with high mechanical properties that allow this car to withstand heavy earth environments and even strong shocks caused by different objects.

In this project, the Cyber truck car will be meshed by using ANSA software, taking into account, the shape errors that the initial car surface model has; all the errors found on the car surface will be fixed and finally, every car component will be meshed and refined using ANSA.

OBJECTIVES

Fix the cyber truck surface shape errors using Topo tools provided by ANSA.

Determine the best limits that each car component should have by measuring the cavities between the component surface.

Mesh and refine the cyber truck meshing, using different mesh cell side sizes in each car component, making sure the mesh will not have off elements.

ENGINEERING DEVELOPMENT

Using the topo tools shown in all the projects previously performed (projects are named in the references section), the car surfaces fit as shown in the following picture.

The car is split to fix the sections that are geometrically wrong easier. Also, the fixed surfaces are named depending on the function each one will have on the car; In the image below, PID function is already used and a color underscores each part of the car.

Likewise, the car parts shown in the PID table above are:

• CYBER TRUCK BODY

• CYBER TRUCK LIGHTS

• CYBER TRUCK WINDOWS

• CYBER TRUCK WHEELS

All the parts shown above must be measured and their minimum required length must be selected by these measurements; Thus, the mesh parameters selected for each component will be:

Cyber Truck Component	Mesh-cell side size (mm)	Minimum length	Maximum length	Skewness
Body	6	3.5	7	1
Wheels	3	1	4	1
Windows	3	1	4	1
Lights	5	3	7	1

All these parameters must be entered one by one in the Quality Criteria tool on ANSA software, in the picture below shows how the mesh parameters used for wheels and windows mesh are entered.

As the same way, the target length and the type of surface mesh are entered too in the Mesh Parameters box.

Once the mesh parameters selected are entered, the next step is to select the perimeter and macros from each part and then, enter the target length that the mesh cell size will have.

Now, to improve the off elements that the program throws when the meshing is generated, it is necessary to use the meshing tools that ANSA provides as well as the move tool, shown above, which increase or decrease one of the mesh cell sizes by moving the node that the user requires to move.

• Before using the move mode

• After using the move mode

Also, the reconstruct tool is used to regenerate the mesh over the surfaces selected, but in this new mesh, the program will take the off elements and will try to mitigate them from the new mesh result.

Finally, the new step is to generate the wind tunnel on the car model, however, because of the computer CPU cannot bear the weight that the volumetric mesh triggers, this wind tunnel will not be shown in this project. Nevertheless, it will be shown how to get the wind tunnel geometry on ANSA.

The wind tunnel will measure 65 m x 10 m x 20 m (L x W x H), so, using the ANSA tools for generating new surfaces, these new surfaces will be created at the bottom, top, front, back, and sides of the car body. Thus, using the volume detection tool and neglecting the car body from the volumetric mesh generation, the wind tunnel will be got.

RESULTS

As it was described on the challenge statements, the off elements must not appear in the finishing meshing from each cyber truck car component. So, the following prictures show that every car part does not have any single off element that affects the mesh parameters and quality. The car components look like:

• CYBER TRUCK BODY

• CYBER TRUCK WHEELS

• CYBER TRUCK WINDOWS

• CYBER TRUCK LIGHTS

In this case, there are not many elements in the car, however, even though there are not too many parts, the elements in each component are a lot; the elements obtained for each component are:

Cyber Truck Component	Number of elements
Body	2154017
Wheels	2899136
Windows	1829087
Lights	15440
Total elements	6897680

Furthermore, the finishing Cyber Truck model obtained shown above looks like the following images:

• COMPLETE CYBER TRUCK CAR

And the wind tunnel without surface and volumetric meshing, will look like:

• WIND TUNNEL WITHOUT VOLUMETRIC MESH GENERATION:

The reason why the wind tunnel was not meshed is due to the computer that the project developer cannot withstand the CPU weights that the meshing generation triggers. Sorry for the inconvenience.

CONCLUSIONS

Cyber Truck meshing and refinement can be difficult because of the cut surfaces that this one has, introducing some errors that sometimes take much time to figure out. ANSA software gets easily the error position and allows the user to figure out these issues quickly.

As it was explained in the challenge referenced below, the flow field modeling requires high computational resources because of the mesh elements must first be volumetric and, each volumetric element must be small enough to get an accurate result of the physical magnitude value that the primitive parameters have within the cubic cell.

ANSA is an incredible CFD software that makes the meshing of complex geometries easier work. All well-qualified CFD engineers should handle perfectly this program.

REFERENCES

https://www.slashgear.com/1211199/the-tesla-cybertrucks-long-and-complicated-history-explained/

https://skill-lync.com/student-projects/week-4-challenge-cfd-meshing-for-bmw-car-366