Week 4 Challenge : CFD Meshing for BMW car

Aim:
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. After meshing the half model, Do symmetry to the other side.

Objective:
Target lengths for the different parts of a model are as follow:

Body - 3 mm
Lights - 4 mm
Grills - 1 mm
Rims and Tyres - 2 mm
Optical Rear view mirror - 2 mm
Window - 2 mm
Silencer - 3 mm
Logo - 1 mm

• Procedure:-
  1.) If we see the Geometry closely, we will notice that the parts are not in the correct shape so as to change its shape we will change it's resolution.
  2.) After that we wil do a Geometry Topo Cleanup.
  3.) Since the car is symmetric from the middle to any end, we can delete one-side of the car and perform the necessary operations on the car and use symmetry option to produce the complete car.

4.) We can now start with the topo clean-up by removing the single and unnecessary triple cons. First click on topo and box select the entire to identify or joins any unjoined single cons or triple cons so that we can identify the required clean-up accordingly, So beginning with FRONT GRILL AREA. It must be noted that we need to modify the lower front grill into a single Internal Volume.

5.) If the LEFT SIDE GRILL part is taken into Consideration we will witness Intersection Errors and Distorted Geometry as shown in the figure.

We will Insert an new surface between in somewhat middle part so as to remove Distorted part using new faces coons option, and then after removing the unwanted Distorted part will lead us to geometry we want.

6.) Coming to the Third and FINAL GRILL same procedure is repeated,making the grill as Single Internal Volume
a) Removing Unwanted Overapping Surfaces from the back side.
b) Using Planecut Option so as to remove excess area from the Grill Part.
c) Removing Geometric Intersection Errors.

7.) Coming to the WINDOWS, REAR LIGHTS, ROOF REGION AND LOGO.
a) Delete the triple cons or extra surfaces to remove the triple cons, these double surfaces are not necessary since we need to have a single volume.
b) Do the same for windows, rear lights and roof area where extra internal parts are present which is of no use to create surface or volumetric mesh.
c) The logo of the car is under a sinlge surface, therefore using project cons, create a separate surface and delete the extra surfaces
to maintain a single volume.

8.) If we the observe the DESIGN FEATURE AND MIRROR Closely there are Triple Cons and Double Surfaces from inside view.
a) Perform topo and identify the triple and single cons, and delete the extra unwanted surface to maintain a common volume.
b) Use the intersect option to identify the triple cons at the intersection area and can delete the smaller surfaces individually.
c) Extended the single cons on the adjacent surface to create triple cons and delete the unwanted surfaces by doing that.
d) Delete and re-create surfaces accordingly to have a smooth and perfect shape at tight corners. Also uncut the lines which are necessary which might cause trouble during meshing.
e) Isolate the mirror and perform topo clean-up, hide the surfaces blocking the the triple cons view.
f) Delete the extra surfaces and create a single volume, also at the car and mirror connection region perform extend on the car surface and create a single volume by deleting the extra surfaces.

8.) WHEEL AND BASE REGION
a) Isolate the wheels to perform geometry clean-up, to rectify the triple cons, hide the surface blocking the view and delete the overlappng surfaces causing triple cons.
b) Create larger surfaces after deleting smaller surfaces which are parallel to eachother.
c) The base of the car is intersecting with the tyre, therefore we need to delete the excess surface and also delete the extra design surfaces which cause smaller edges,
this causes problems while creating mesh.
d) Therefore we need to clean the entire base and create new surfaces accordingly having smooth edges.
e) After making the surface changes, we need to check if the base surfaces has no intersection with the tyre region.

9.) After checking and performing topo-clean up for the entire half car model. We need to perform geometry checks to find small cracks are unchecked faces extra which is not good for the geometry, therefore we need to perform checks and clean the geometry accordingly.

• ASSIGN PID TO EACH AND EVERY COMPONENTS SO AS TO PROCEED FOR SURFACE MESHING
• QUALITY CRITERIA

We need to mesh the components individually since the given mesh targets are different for each PID regions. Assign the mesh parameters and quality parameters for each PID accordingly, assigning the correct min and max length will reduce mesh failure and off elements.

• SURFACE MESHING

1.) GRILLS & LOGO (1 MM-MESH)

2.) MIRROR,TYRES & WINDOW (2MM-MESH)

3.) BODY AND SILENCER (3 MM-MESH)

4.) LIGHTS(4-MM)

• PERFORMING SYMMETRY ON THE CAR MODEL

a.) Perform symmetry under transform option to create a exact same opposite body of the car to create a full body car.
b.) Use the copy option and select the half body car and diselect the logo since we dont need a copy of the logo.
c.) After choosing the model, middle click mouse, we get a window, choose symmetry and choose mirror 3 points plane and choose 3 points on the edge to be performed symmetry.
d.) After choosing 3 points, middle click twice and the symmetry is performed, click middle click again to confirm the geometry and complete the process.
e.) There will be few single cons present near the middle section, use paste or other tools to solve the problem.

• FINAL GEOMETRY

• LEARNING OUTCOMES

a. Learnt the complete CFD meshing skill from skratch.
b. Performed various topo clean-ups using different tools.
c. Understood the need of double cons and removing unecessary triple and single cons.
d. The use of symmetry helps in reducing the work time and helps in having accurate results with less work.
e. Create surfaces using the reference hot points by using relative points.
f. Surface meshing for different components and their varying mesh lengths.
g. Using spacing option in surface meshing helps in having varying mesh lengths along the surfaces.
h. Using re-construct option to reduce off elements to a level where we can edited it manually.
i. Using the mesh modifying tools like move, split and smooth options.

TO ACCESS THE MODEL PLEASE GO THROUGH THE BELOW LINK.

https://drive.google.com/file/d/1iQ7UvygK0Wtd8bPEh2r-hQGM7fq7guV7/view?usp=sharing