Week 4 Challenge : CFD Meshing for BMW car

CFD Meshing for BMW car

Aim:To perform surface mesh to Wind tunnel surfaces for BMW car.

Objectives:

1. To check and solve all geometrical errors on half portion and Assign appropriate PIDs.
2. To perform meshing with the given Target length and element Quality criteria.
3. To do symmetry to the other side after meshing the half model .

Procedures:

• Check and solve all geometrical errors

• open the given model in Ansa
• devide the geomtry in half
• perform topo clean up and geometry check
• remove single con,triple con

original geometry

few steps to clean the geometry:

Body:

Light:

Final geometry to perform meshing:

• Assigning PIDs:

• Assiging qaulity criteria by enabling openfoam

• Surface meshing:

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

Logo:

min length:0.4mm

max length :2mm

After correction in topo and remesh and reconstruct:logo:

After correction in topo and remesh and reconstruct:grill:

min length:0.3mm

max length :2mm

After correction in topo and remesh and reconstruct:windows:

min length:1mm

max length :3mm

After correction in topo and remesh and reconstruct:optical rear view mirror:

min length:1mm

max length :3mm

After correction in topo and remesh and reconstruct:rims and tyres:

min length:1mm

max length :3mm

After correction in topo and remesh and reconstruct:lights:

min length:3mm

max length :5mm

After correction in topo and remesh and reconstruct:silencer:

min length:1mm

max length :5mm

To mesh all the PIDs together:

• Perform symmetry :

• select top view

• deselect logo
• select mirror 3 point plane and input data ,no offset

• Geometry check

• error rectified

• Creating Wind tunnel:

The measurment for wind tunnels are as follows

• 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

• Meshing the wind tunnel:

base:

top:

rear:

front:

sides:

Overall :

Volumetric Mesh:

Perform autodetect:

Required volume:

Delete unwanted volume and perform remesh.

Ansa file link:

https://drive.google.com/file/d/1EdQstrrjc35uDWZZk7pzke3IT25VDXoz/view?usp=share_link

Learning outcomes:

• topo clean up
• surface mesh
• quality criteria
• target length
• wind tunnel creation
• voumetric mesh

Results:

• 1 unmeshed after deleting unwanted volume.
• we have to perform remesh to solve this.

Conclusion:

Repeated changes have to make to get the desired cfd meshing.Remeshing has to be performed to see te final outcome.Cfd meshing is performed upto performing surface mesh to Wind tunnel surfaces.