Meshing of BMW M6 model

1.0 Objective: Mesh the BMW M6 Model and create a wind tunnel for the study of flow of fluid for analysis.

2.0 Procedure : for creating a CFD mesh we must convert all the volume elements to surface elements.

step 1 :first we import the model in ansa and we check for the geomentrical errors for the given model.

figure 1.0

• figure 1.0 represents step 1.

step 2: now we check for symmetry in the geomentry, so that we can work on the errors on one side and the same can be duplicated , this would save time in meshing and clearing the topological errors. Now we have found out that there is exact symmetry of the geomentry so we can delete one half clear all the topological errors and mesh the model and duplicate the half and complete the model.

figure 2.0

• figure 2.0 represents step 2.

step 3 : now we start working on the topoligical errors, we clear the errors near the door region, we intersect the surface delete the unwanted surfaces and remove the triple and single cons convert them into double cons.

figure 3.0

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figure 3.3

• figure 3.0,3.1,3.2 represents before clearing the error and figure 3.3 represents after clearing the error.

step 3.1 : now we work on the symbol region, the extra surface of the symbol is removed , the letters of the symbol is removed and a flat surface is created which becomes a part of the hood.

figure 3.1.0

figure 3.1.1

figure 3.1.2

• figure 3.1.0 and 3.1.1 represents before clearing the error and figure 3.1.2 represents after clearing the error.

step 3.2 : now we work on the grill region, here we need to convert the volume entities to surface entities, delete the extra surfaces convert the cons to double cons.

figure 3.2.0

figure 3.2.1

figure 3.2.2

figure 3.2.0 and 3.2.1 represents before clearing the error and figure 3.1.2 represents after clearing the error.

step 3.3: now we follow the same procedure for the other 2 grils as well, for the last grill we cut the extra part of the grill in order to intersect with the body.

figure 3.3.0

figure 3.3.1

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figure 3.3.3

• figure 3.3.0, 3.3.1 and 3.3.2 represents before clearing the error and figure 3.3.3 represents after clearing the error.

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figure 3.3.6

figure 3.3.7

• figure 3.3.4, 3.3.5 and 3.3.6 represents before clearing the error and figure 3.3.7 represents after clearing the error.

step 4.0 : now we convert the other volume elements to surface elements by deleting the inner surface of the windows, mirror ,windshields head lights and tail lights.

figure 4.0

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figure 4.8

• figure 4.0,4.1, 4.2, 4.3, 4.4, 4.5 and 4.6 represents before clearing the error and figure 4.7 and 4.8 represents after clearing the error.

step 5.0 : now we clear the other topological errors on the body of the car and fix the exhaust region, for this we make use of extrude and extend option from faces in order to intersect the exhaust with the body.

figure 5.0

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figure 5.3

• figure 5.0, 5.1 and 5.2 represents before clearing the error and figure 5.3 represents after clearing the error.

step 6 : now we work on the wheels we remove the triple con by deleting the extra surface, and we delete one of the wheel due to alot of damage that happened during converting the file,now we can copy the deleted wheel from the existing wheel.

figure 6.0

figure 6.1

figure 6.2

• figure 6.0, and 6.1 represents before clearing the error and figure 6.2 represents after clearing the error.

step 7 : now we assign the pid for different pids using the model browser, now we seperate the body, grills, lights and other pids into the respective model browser.

figure 7.0

• figure 7.0 represents step 7.

step 8 : now we mesh the model and also work on the quality parameters for the given criteria and make sure that is model is free from errors, for removing the errors we make use of the mv move, reconstruct ,smooth, cut, mv surface options avaliable in the mesh mode.

figure 8.0

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• figure 8.0, 8.1, 8.2 and 8.3 represents step 8.

step 9 : now we create reference points in accordance to the given criteria for constructing a wind tunnel. for these points we create curves for a better view and presentation, we create the points using the refernce option under new point option.

figure 9.0

• figure 9.0 represents step 9.

step 10: now we create the wind tunnel, for which create coressponding reference points using the reference option under the new points option. now we create the points according to the given criteria and connect these points with curves, now we create 2 more reference points for the previously created points in order to define a plane, bassed on the previous points postion we make changes in directions of the new points , for example if the point is in x plane the the new point which we create will on the x plane but with differnt y and z coordinates so that the 3 points define a plane. now we repeate this process for all the 4 basic reference points which we created and we create a plane using the plane option under surface option, then intersect the palne and delete the extra surfaces, by this we get a wind tunnel for the required parameters.

figure 10.0

figure 10.1

• figure 10.0 and 10.1 represents step 10.

3.0 Learning outcome:

• from this we learnt the different ways of removing the topological errors from the model, learnt two new tools which is extent and extrude.
• learnt how to create symmetry of the objects.
• we learnt to correct the mesh quality parameters using various tools like, reconstruct, smooth,cut, mv surface, mv move.
• we also learnt to create wind tunnel for the model for the analysis of flow of the fluid.

4.0 Conclusion :

• we have cleared all the topolgical errors, meshed the car model and rectified the mesh quality parameters and created a wind tunnel for analysis of flow of fluid.