Week 4 Challenge : CFD Meshing for BMW car

Aim:

To perform meshing on the BMW car model by starting performing geometry simplification and geometric error rectification, and satisfying the necessary quality criteria.

Procedure:

First we will the identify that the model is axi symmetric, so we will remove one half part which contains more error and we will retain other half , perform all cleanup and then will mirror the part. After performing the geometry check manager, we will get 4 errors and 300 warnings in the geometry part and 28 intersection errors. First we will select the grill part, perform the cleanup. Then with second grill , followed by the third grill. Then we will perform the cleanup on the glass, BMW Logo, Body , a region near to the front door which is little complicated, then floor cleanup and finally followed by the wheel cleanup. Then PIDs are assigned.

The above figure shows the grills after the geometric cleanup is done.

The above figure shows the body of car after cleanup.

The above figure shows the wheel of car after cleanup.

The above figure shows the assigning of PIDs to the parts.

The above figure shows the PIDs assigned to the car.

Now we will check the quality parameters , enable skewness, minimum length and maximum length. Skewness is given as 0.5, minimum length as 0.1 mm and maximum length as 7 mm.

The minimum length should be length than minimum target length used i.e 0.5 mm so we use 0.1mm; similarly maximum length should be greater than maximum target length used i.e, 5mm , so we used 7mm.

Then we will perform meshing based on the question given: 1 mm for grills, logo; 2 mm for windows, tyres and mirror; 3 mm for silencer, body and 4 mm for light. We use spacing then give perimeter and macros with necessary minimum and maximum target lengths , then perform meshing using CFD mesh algorithm.

Learning outcome:

To perform meshing on BMW car model, and study the quality parameters like skewness, minimum and maximum length and performing deletion of off elements using improve reshape method etc and changing the skewed elements.

Results:

The above picture shows the triangular elements formed on the grills.

The above picture shows the triangular elements formed on the wheels.

The above picture shows the triangular elements formed on half part of the car.

The above picture shows the triangular elements formed on full part of the car.

The total number of triangular elements obtained are 854331.

Conclusions:

The surface meshing has been done on the body of the BMW car. The quality parameters has been checked and the offelements has been removed. The wind tunnel construction can be done, but it can computationally time consuming and the system specification needs to be sufficient.