Week 4 Challenge : CFD Meshing for BMW car

Aim: CFD Meshing for BMW car.

Procedure:

1. Open the model in ANSA.

2. Change the perimeter lenght to 1 mm, Orient and topo the model.

3. Do the geometry cleanup.

Since the model is symmetry delete the half model, do cleanup and refect it.

4. Check the geometry using check manager.

There should be no error other than single con in the middle deleted region.

5. Create and assign different PID as per the components.

6. Delete the empty PIDs and convert the card images as per the openfoam solver using compress option.

7. Do geometry cleanup and mesh the model as per the given quality criteria.

8. Do the symmetry operation to reflect the model.

9. Use the check manager to check for errors.

10. Create a wind tunnel surface

Wind tunnel dimension should be 4x distance from front end, 6x distance from rear end, 3x distance from top end, at bottom we keep small distance from base of car (assume 75 mm) since we are not interested wind flow from below the car, side face of wind tunnel should be x distance from side end.

X is the maximum length of a car.

a. Measure the X distance.

X = 1308 mm

b. Create a centre from bottom face and to arround 75 mm distance using points relative option.

c. Create a front base point at 4x distance + centre to front distance.

Distance = 1308 *4 + 882 = 6114 mm

d. Create a point at rear side.

Distance = 6*1308 + 550 = 8398 mm

e. create a point at top at 3x distance.

Distance = 3 *1308 = 3924 mm.

f. create a point in side direction.

Distance= 1308 + 230 = 1538 mm

g. create all base point to the top distance.

Distance = 1308*3 + 390 = 4314 mm

h. create a curve and after that create a surface for tunnel and assign different pids.

11. Mesh the wind tunnel.

Mesh the wind tunnel finner to near the car model and courser mesh to the farer region.

Top region 100 mm target length.

Bottom region 20 mm target length.

Front and rear region use spacing option to get increasing mesh length from bottom to top.

12. Define the volume and delete the volume other than wind tunnel.

Conclusion:

Meshing wind tunnel volume with tetra elements for car model was done succcessfully.