Week 4 Challenge : CFD Meshing for BMW car

Aim:

To check and solve all geometrical errors on half portion and Assign appropriate PIDs. Perform meshing with the given Target length and element Quality criteria.

1. Target lengths for the different parts of a model are as follow:
2. Body - 3 mm
3. Lights - 4 mm
4. Grills - 1 mm
5. Rims and Tyres - 2 mm
6. Optical Rear view mirror - 2 mm
7. Window - 2 mm
8. Silencer - 3 mm
9. Logo - 1 mm

To mesh Wind tunnel surfaces and the model should clear the quality criteria (i.e. Off elements should be zero).

Procedure:

First select  topo and shaded mode intially from the deck

Given geomentry model check and do topo clean up intially from face deck then change resolution in settings to 1mm perimeter length move for further step.

After that the model is symmetric so we can delete the half part and work on the other half then we can copy this half to other side don't delete the logo since its not symmetric.

Before working on this we need to make this as single inside volume as we work on for body and four tires as seperate volume so total it should have only Five volumes.

Then work on the model by part by part first we can go with grills.

First grill: 

then work on the red cons and try to simplify the work as much as possible just use cons>project and faces>delete option to work on it.

final grill geometry should not have any geometry error or red cons

The red cons will be present on the edges were the other half of will meet so no need to clear that.

Second grill:

 you can see it has lot of triple cons that must be due to overlapping surfaces so just delete the faces that causing them.

then when zoom in you can see lots distortion on edges of the grill so we can cut 0.2 percentage of total length consider the range 0-1 use the Hotpoints>parametrical and select the edges as shown all sides to create hotpoints and cut them.

Create new face so that it intersects them as shown then use intersect option.

After that just delete the unwanted surfaces and faces.

Third grill:

Here the same procedure as other grills clear the geometry by using following options step by step.

 

    

These options are major tools used repeatedly to clear the geometry of the grill which is simple work.

The final output grill is

Logo:

logo causes intersection error and geometry error just the body face is intersecting on it so just poject the cons and delete the face on body and also delete the faces causing the triple con.  

the above parts are the major and difficult parts others all are small geometry clearence.

Side body:

In this there is a face we need to extend and delete the faces and simplify it.

Window:

Then there are triple cons in windows just deleting the ovelapping surface solves that issues.

Side mirror:

Finished geometry

After that side mirror and body contact point has a overlapping surface and we have to make a single volume so just projecting the cons and deleting the surfaces will solve it.

Floor clean up :

By doing this will also clear the intersection of surfaces with tires and silencer.

so then small surfaces and intersections will be there clear them step by step then check them.

Then go for surface mesh 

as given target length do them one by one

1. Target lengths for the different parts of a model are as follow:
2. Body - 3 mm
3. Lights - 4 mm
4. Grills - 1 mm
5. Rims and Tyres - 2 mm
6. Optical Rear view mirror - 2 mm
7. Window - 2 mm
8. Silencer - 3 mm
9. Logo - 1 mm

Then give the target length using perimeter option.

Then give the quality criteria 

 

Then transform this body copy on other side.

There might be some off elements because we have set quality criteria so to solve it.

use as shown in image then either go for reconstruct or reshape if off elements reduces its ok if not stop this and move the grids manually.

Then the total work on the bmw is done.

Wind tunnel:

To create wind tunnel we must use following measurement.

First measure the car length using measure from top deck.

Then create points as first create center point of car then use relative option and place the points as per measurement.

After placing four corner points in bottom draw curves then create face using face>new>cons option.

Transform the bottom surface to top and cover side surfaces.

 

it should look like this then go for mesh for using standard target length such as 

bottom - 30

top - 100

sides use growth rate by giving limits 30 - 100 and do meshing individually for meshing these it may take some time so be patient it depends on your own system specs.

Top side 

 

Bottom side

 Model Link :

https://drive.google.com/file/d/1PHSwuDlNDRGf7-qzo8DYXE_AhQ5xNDUt/view?usp=sharing