Week 4 Challenge : CFD Meshing for BMW car

Downloadin and Importing the Geomtry to ANSA and then then doing the TOPO-CLEANUP.

This is the geometry of the car in wire frame mode, with all the single, double and Triple cons. We have to rectify the all the single and triple cons to double cons for the perfect geometry.

Now the geometry of the car with Shadow and wireframe mode.

There we can see the errors of the geometry so that we have to rectify the geometry.

As we can the see the body as symmetric, we will cut the body to half to rectify the errors and after rectifying the errors will be mirroring the other to the deleted portions of the body.

Cutting the car into half and doing the topo clean up, as shown below:

Half of the body in the in the wireframe mode.

While cutting the body make sure that we do not select the logo of the car as the logo is not symmetric.

Further more we need to do the topo-clean up of the car with seperate elements so that the topo clean is good.

Topo clean up of grills, as we can see the single cons and triple cons of the grills have been eliminated and now we can only see the double cons as a reflectio of perfect geonetry.

Same of grills here also:

Now we have to do similar with all the case.

For Windows:

BMW logo:

Do the similar with tyres, body, rear view mirrors any other left region.

After doing the topo-clean up we have to assign the PID's for the car.

Based upon the color of the PID's we can see the element present in it.

Furthermore we have to do the Surface Meshing of the geometry before mirroring it.

By giving the element size we have to also give the quality criteria of the element independently.

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

1. Body - 3 mm
2. Lights - 4 mm
3. Grills - 1 mm
4. Rims and Tyres - 2 mm
5. Optical Rear view mirror - 2 mm
6. Window - 2 mm
7. Silencer - 3 mm
8. Logo - 1 mm

First we will do with smallest part of the element and slightly go the bigger paet of it.

Below mention are the quality cirteria of the geometry.

For logo min and max length are 0.4 and 0.2, applying this conditions and execting the mesh we get the off values as

After reconstruct of the mesh the off values again changes

Similarly for grills min and max length as 0.2 and 2 applying this conditions and execting the mesh we get the off values. After doing the reconstruct.

Similarly for Windows min and max length as 1 and 3 applying this conditions and execting the mesh we get the off values. After doing the reconstruct.

Similarly for lights min and max length as 3 and 5 applying this conditions and execting the mesh we get the off values. After doing the reconstruct.

Similarly for rims and tyres min and max length as 1 and 3 applying this conditions and execting the mesh we get the off values. After doing the reconstruct.

Similarly for silencer min and max length as 1 and 5 applying this conditions and execting the mesh we get the off values. After doing the reconstruct.

Similarly for optical rear-view mirror min and max length as 1 and 3 applying this conditions and execting the mesh we get the off values. After doing the reconstruct.

Similarly for body we dont be ding the min and max length here becuase of the attached small surface present there we will be directly meshing it by giving the target length and applying this conditions and execting the mesh we get the off values. After doing the reconstruct.

To find out the all the surface meshing elements enable all the geomtry of the elements and then find it out.

In Meshing we can see the change in the meshing size from one elemement to another due to the presence of continuity mesh in it.

After doing the surface meshing mirroring it to the other side of the geometry to the symmetrical part of it, but dont select the logo of it.

Mirror it by Transform.

Now enclosing the tunnel for the car, the conditions for enclosing the tunnel is:

1. Front Face 4X from the front part of the car
2. Rear Face 6X from the rear part of the car
3. Top face 3X from the top
4. Side faces X for each side.
5. Bottom face we have to hust take for a smaller portion till the tyres gets submerged in it.

X is the length of the car from front to the top.

After doing the enclosure mesh it with top face as 100mm and bottom face as 20mm. Use spacing options for meshing.

After meshing the results are shown below:

The surface mesh has been completed for wind tunnel and the BMW car.

Thank You