CLEAN UP THE TOPOLOGICAL ERROR AND CREATE THE SURFACE MESH AND VIRTUAL WIND TUNNEL FOR BMW M6 USING ANSA

OBJECTIVE:-

The objective of the assignments are:

• Carry out the Topological errors present in the model and Eliminate if they are present.
• Generating the surface mesh of the BMW M6.
• To creat virtual wind tunnel of the BMW M6.

PROCEDURE

1. Cleaning the topological errors
2. Assigning the PID
3. Generating the surface mesh
4. Fixing the mesh errors
5. Creating the virtual wind tunnel.

Cleaning the topological errors

• Import the file BMW M6 file to ANSA page as shown in the below figure.

• As we see in the above model we can observe that lot of errors(single and triple coons) are present in the model and we can eliminate that errors one by one in the upcoming steps and covert into double coons.
• And we strat the work with the left half of the model and after completing the left we can copy it over the other side.
• In the first step we go to set the model in PID and than set the quality criteria parameters and enable the cross hatches i,e shown in the figure below.

Step 1:- Cleaning the topological error as follows

• Now we can observe above picture lot of errors are present i,e single and triple coons we can eleminate that errors by deleting the unwanted surfaces by using delete tool and all are converted into double coons as shown figure below.

Side grill:-

• Clean up the geometry by deleting the unwanted surfaces by using delete tool.
• And then we create new surfaces by using fitted tool to remove the single and triple coons are present in the model and that are convrted into double coons. Below figure shows after cleaning up the geometry.

Intake grill:-

• Clean up the geometry by deleting the unwanted surfaces by using delete tool.
• And then we create new surfaces by using fitted tool to remove the single and triple coons are present in the model and that are convrted into double coons. Below figure shows after cleaning up the geometry.

Bottom grill:-

• Clean up the geometry by deleting the unwanted surfaces by using delete tool.
• And then we create new surfaces by using fitted tool to remove the single and triple coons are present in the model and that are convrted into double coons. Below figure shows after cleaning up the geometry.

Wheels:

• As we observe above the one wheel having a lot of errors as compare to other three so we can patch of that wheel it requires a lot of time that's why we have one option i,e copy we work on the front left side wheel when we complete that just we delete the right front side wheel than we copy the left side wheel to right by using copy tool.

Body:-

Before

Here lot of errors are present in the model before we starting the work and now we clear all the topological errors as shown in the below figure.

After

Boundary Condition:-

Setting the PIDs for diffirent parts of the BMW M6 model and assigning them with diffirent names, seperate groups were also created for seperate PIDs for ex: for all the wheels in one group, body, grills, windows, lights and exhaust.

• Under those groups the single PIDs are been assigned.
• The geometry checks were taken to verify any errors, single cons, triple cons, needle surfaces, convex cons, concave cons, mixed cons and fixed all of them and proceded to surface mesh.

• After clearing all the topology the element length was specified as given for all the saperate PID's

Element	Length Size in mm
Body	3
Lights	4
Grills	1
Tyres	2
Rims	2
ORVM	2
Windows	2
Silencer	3
Logo	1
Element	Tria

• The above shows the perimeter length of the diffirent parts of the car.
• After assigning the length it was meshed using the free mesh under the mesh generation.

• It was checked for the surface mesh checks and cleared all the intersections, penetraion, sharp edges, mesh quality and fixed all those errors.

Mesh parameters:-

• Quality criteria for the mesh parameters were checked minimum length, maximum length, skeweness, angle cleared all the errors fixed them finally.
• skeweness is one of the primary quality measures for the mesh. Skeweness determines how close to ideal a face or cell is.
• Minimum length which is given in the quality criteria parameters is a target which wont go below that.
• Maximum length which is given in the quality criteria parameters is a target which wont exceed than the maximum legth given.
• Cleared all the above quality criteria errors and fix them.

• Wind tunnel created after fixing all the errors

Wind tunnel dimensions

Let X = Total length of the BMW M6 car and measured value taken as 1300 mm.

4X = Front of the car i,e 5200 mm.

6X = Rear of the car i,e 7800 mm.

3X = Top of the car i,e 3900 mm.

Bottom close proximity with tyres.

1X = For centre plane for left and right sides i,e 1300 mm.

Wind Tunnels:-

Wind tunnels are large tubes with air moving inside. The tunnels are used to copy the actions of an object in flight. Researches use wind tunnels to learn more about how an aircraft will fly. NASA uses wind tunnels to test scale models of aircraft and spacecraft some wind tunnels are big enough to hold full-size versions of vehicles. The wind tunnel moves air around an object, making it seem like the object is really flying.

Conclusion:-

• The topology was been cleared with all the double cons which is needed for volume to create.
• The diffirent mesh sizes for all the PID's were assigned and surface meshed by refining the mesh and as well as errors
• After that wind tunnel was created.