Week 4 Challenge : CFD Meshing for BMW car

Aim

To perform volumetric meshing on the given model of BMW car geometry.

Objective

For the given model, 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

Procedure

Geometric cleaning

First of all we have to clean the geometry to make it free from errors ,single coons, triple coons etc..

• This the model we got initially
• We performed Topo option to fix some errors
• Initialy the coon resolution is not smooth
• Here we use fine option in auxilliary section to make coon resolution smooth
• • We removed half of the model for making the process easy
  • After meshing we use copy -symmetry option to get back those symmetric half portion
  • We have to avoid chances of formation of seperate volume
  • If seperate volume are there , may cause problems while volumetric meshing
  • In Grill portion we have to close the surface to avoid the formation of seperate volume
  • In optical rear view mirror we must avoid the fromation of seperate volume
  • We need the whole car as a single volume
• • After this we have to fix the under body part
  • In under body part we have to remove some extra surfaces to celan the surface
  • We use Curve option to make reference curve on the deleted surface
  • We utilize this curve as a coon to create new surfaces

  We assigned PIDs for different body parts

• Before meshing we have to uncut some coons
• We have to remove some coons which are very close to each other
• If there is coons which are at a distance smaller than our target length,may cause off elements while meshing
• Here we make two new cut to uncut or remove the one of the close coons
• Coon which is to delete is selected in such a way that in absence of that coon there is noc ahne in geometry
• We measured some parts to check whether it is smaller or not than target length
• Here also we have to close the surface to avoid formation seperate volume
• For that fist we projected bigger coon to the small parts of grill
• We projected front surface of all small surface grill
• Then we use project cut option to make the cut around the whole small surface
• Then we deleted those small portion
• Here we projected hot point to the above coon for creating new surface

• Surface meshing

  Next we started surface meshing

  • We used spot mesh for mesh generation
  • We set quality criteria for minimum length, maximum length and skewness
  • Skewness is the measure for equalateral triangularity of mesh
  • We checked our model for small surafces ,close coons etc.. and avoided chances of creation of off elements while meshing
  • Here we have off elements due to skewness
  • skewness is measure of mesh element's equlateral triangularity
  • Here we fixed the off elements mnaually by using move tool

  • Rear view mirrors

    • Then we meshed rear view mirrors
    • After meshing we freezed that particular PID
    • Freezing make the perimeter free from disturbance from srrounding perimeter while further meshing

    • Silencer

      • Here we used automatic methods to fix off elements
      • We used automatic methods like
      • Reconstruct
      • Fix quality
      • Reshape
      • Smooth