Project 1 : CFD Meshing for Tesla Cyber Truck

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

Step Involved:-

• TOPOCLEANUP
• PID's Assign
• 2D meshing with different mesh length for different PIDs
• Wind Tunnel creation
• Volumetric meshing

Original Geometry:-

This is our raw geometry when we activated single cons we can see whole geometry covered in single cons, To avoid single cons do topo for whole geometry this will solve issue of single cons.

Geometry after applying TOPO tool

All single cons are converetd to double cons

Step 1-Topo cleanup

• Create cut on geometry so that geometry could be divided in half
• Delete half geometry, Always delete the side where you see less work had to be done in order to fix geometry.
• Patch open surfaces
• Delete overlapping and extra surfaces
• convert triple cons to double cons

Diving Geometry after creating cuts in middle

I have deleted the side on which there was more work required to be done in order to fix problems. Now work on half part, This is the best way to workon geometries which are symmetric.

Creating new surface to patch holes and clear single cons-

Patching First open surface

Patching second open surface

Patching third open surface

In below image image you can see brown color cylindrical surface penetrating with body, that brown part is part of wheel PID and delete that part then patch holes appeared on body and wheels seperately.

Deleting wheel PID part and then patching hole which appears in body and wheels separately

Sharp Edges

You will often face very small sharp edges on geometry which can be seen only when we zoom in or when we do geometry check.

• we can directly delete those sharp edges
• If we cannot directly delete them, create cuts and seperate those edges from large PIDs and tehn delete them
• Delete hot points which are not required

Geometry check after Topo cleanup

By doing we check there are no unnescessary single cons present and we are good to go for symmetry

CREATING SYMMETRY

• Go to transform tool and choose copy, a dialogue boz will appear , choose entity and drag your mouse doing right click to select whole geometry and do right click.
• In the new dialogue box which appears choose symmetry and three points plane
• Choose any three points to automatically fill required coordinates.

• click on apply and tehn click ok in the new dialogue box which appears . Don't make any changes.

Symmetry Done

Check for single cons as this common error after doing symmetry and solve them by using patch tool or by creating new surface.

Geometry Check Done

Geometry is ready to go for meshing

PID’s Assigned

Step 2- 2D Meshing

Mesh length for differnt PID's

Roof top- 3mm

Lights - 2mm

Tyres - 2mm

Windows -4mm

Body- 5mm

Light Meshing-

Quality criteria and mesh parameters for light

• Mesh length is 5mm
• After giving quality criterias, give length parameters and macros
• select length parameters and choose PID by doing right click and dragging cursor over PID. Then do middle click
• Dialogue box will appear, give mesh length 2mm and click ok
• Similar do for macros
• Then select spot mesh and choose visible mesh, you can see mesh on PID
• In order to check if geometry is failing on quality criteria go to hidden mode and go to entity mode while using hidden mode.
• you will off elements. select reconstruct option and choose visible and execute reconstruct option. Reconstruct option will solve most of off elements and remaining off elements needs to be solved by findind why mesh is failing, mainly this happens due to formation of meshes smaller than specified criteria.
• Go to topo mode and use cut options to cut or recreate cons where mesh is failing.
• Use reconstruct option to automatically solve maximum errors, rest handle by yourself.
• use move tool to change dimension of mesh , this will solve most of off elements, specailly those off elements which are due to min & max length.

Body Meshing-

Quality criteria and mesh parameters for Body

• Mesh length is 20mm, use high value of mesh because geometry has large dimensions.
• After giving quality criterias, give length parameters and macros
• select length parameters and choose PID by doing right click and dragging cursor over PID. Then do middle click
• Dialogue box will appear, give mesh length 2mm and click ok
• Similar do for macros
• Then select spot mesh and choose visible mesh, you can see mesh on PID
• In order to check if geometry is failing on quality criteria go to hidden mode and go to entity mode while using hidden mode.
• you will off elements. select reconstruct option and choose visible and execute reconstruct option. Reconstruct option will solve most of off elements and remaining off elements needs to be solved by findind why mesh is failing, mainly this happens due to formation of meshes smaller than specified criteria.
• Go to topo mode and use cut options to cut or recreate cons where mesh is failing.
• Use reconstruct option to automatically solve maximum errors, rest handle by yourself.
• use move tool to change dimension of mesh , this will solve most of off elements, specailly those off elements which are due to min & max length. Using move tool will eventually solve 98% of off elements.
• To use move tool identify areas where off element is and then drag meshes there too clear off elements.

Windows and Rooftop Meshing-

Quality and mesh parametrs for windows and rooftop.

Mesh length is 20mm, use high value of mesh because geometry has large dimensions.

Tyre Meshing-

Meshing For Door Handle

Door handle is a part of body but due to its small size I have meshed it with lower mesh length.

Step-3 Creating Wind Tunnel-

We will create a wind tunnel around car

Measurment for wind tunnels are-

• Consider length of car as X
• Keep wind tunnel at 75mm distance from bottom of car
• Length of wind tunnel from front of car should be 4X, total length of tunnel in front is half length of car added to 4X length
• Length of wind tunnel from back of car should be 6X, total length of tunnel from rear side is half length of car added to 6X length
• Height of wind tunnel should be 3X

Dimension of car

Length of car - 5760

Distance from mid of car to front - 2570

Distance of mid of car to back – 3180

Steps Involved-

• Enable cons
• select relative points option from point tool and select a point in middle of car from bottom side
• A dialogue box will appear, see your coordinate axes, To create a point at bottom of car I will give 700mm with negative sign.
• With reference to that point create a point in front of car at distance 25610mm in X direction & at 37740 in back of car.
• create side ponits atr 5760 on front and back side

Step-4 3D Meshing

• Choose define option available in volumes tool and select wholedb(whole database) and click on ok.
• Volumes created for 3D meshing will appear in a dialogue box
• From dialogue Box select first volumes this is the volume of tunnel and this is what we require.
• All oher volumes are car volumes which is not required so delete them.
• The one PID with blue color we will keep and delete others.

Link to Geometry-

https://drive.google.com/file/d/1EqotfJB3Ur_WdTbkW1J3DUns-ngAWqg4/view?usp=drive_link

Conclusion:

• Working on tesla model gave ideas about different meshing tools available in ANSA.
• Learned surface meshing and Geometry cleanup in much detailed manner. Challenges faced helped to understand tools better
• Learned how to use curve tool, how to create win tunnel with help of points and curves
• Learned about dimensions of wind tunnel, like what dimesnions to give based on model size
• Learned how to de meshing when there are different PIDs with different mesh length in contact with each other
• lerned use of reconstruct and move tool
• worked on how to fix off elements
• Advance topo-cleanup