Week 4 Challenge : CFD Meshing for BMW car

Aim:CFD Meshing for BMW car

objectives: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.

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

• after that we have to performing surface mesh to Wind tunnel surfaces

Procedure:

steps whic we have to fallow to create valumetric mesh shown below

• Geometry import and cheak
• Setting up Properties using set PID command
• Geometry clean up(deleting the unnecessary drawing)
• Meshing
• performing symmetry of the car
• Creating wind tunnel
• meshing wind tunnel

Geometry import and cheak: First steps is to import the geometry into the ANSA by going to FILE>OPEN>IMPORT as shown below.

Geometry clean up(deleting the unnecessary drawing):here we have to clean the geometry by removing the any extra cones,face and hotpoints

• Go to mesh and choose length and enter 1 mm under perimeters to smoothen the sharp curves of the car and give it a fine look.

• Since the car is symmetric,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

• after using the symetry oppareter just delete the one half of the car as shown below

• after doing this we can start the topo clean up of model one by part as shown below

Grills

• first we have delete the all the extra part which is present in the inner part of the grill and also we have to delete the all the single and double and tripple cones and make the one valume as shown below

Front grill region:

Deleting and creating new surfaces:

geometry cleaned grill:

Windows, rear lights, roof region and logo:

• first we have to delete the all the single double and tripple cones present in our geometry and also we have to delete the over laping surface present in our window part as shown below

Logo: In our logo we have single cone also over laping of the surface which we have to remove as shown below

mirror:in our mirror we dont have any error what we have to do is judt do project on the car body and make it one valume as shown below.

Wheels: in our wheel we have many over laping surface that are causing the tripple cone which we have rectify and clean the geometry as shown below.

Body: our body have many intersecting surface which is intersecting on the wheels so we have to clean the all the body.

• in the bottom of the body we have very bad surface which we have to clean up by dleteing the whole bottom body then create the new bottom body using curve to cone option

cleaned body shown below

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 and resolve the issues

in our above body we have cleared all the error present in our body and know our body is ready for meshing

Setting up Properties using set PID command:for setting the pid first we have turn on the crossedge in order to select the face for giving the properties

after that we have to go to PROPERTY then we have to creat the new labels and then we have to give naming to the facing as shown below

• body
• light
• grills
• rims and tyres
• rear view mirrors
• windows
• silencer
• logo

Meshing:After cleaning the geometry we have to create the mesh for one by one part by going to MESH>LENGTH>PARAMETRIC+MACROS after this setup mesh element by going on MESH PARAMETER>CFD MESH as shown below

• Logo:for logo we have to give mesh lenght of about 1mm

• Grills:for grills we have to give 1mm of lenght for meshing

• Mirror:for mirroer we have to give 2mm of lenght for meshing

• Rims and Tyres: for rims and tyres we have to 2mm of mesh lenght as shown below

• Silencer:for silencer we have to give 3mm of mesh lenght as shown below

• Lights:for light wwe have to give mesh lenght as 4mm as shown below

• Body: for body we have to give 3mm mesh lenght as shown below

• Windows: for windows we have to give 2mm of mesh lenght

Performing symmetry of the car:

• After succesfull cleanup and meshing of nhalf part of the geometry we have to do the symmetrt operation on our car
• fore performing symmetrt operetion we have to go TRANSFORM>COPY>MIDDLE CLICK.
• after this one window will open in that window in thaT CHOSE symmetry using 3 points then select 3 points and middle clicl two time then we will get our symmetry succesfully
• after succesful creating the symmetry we will get some cone near our middle region that we have to solve by using paste option

symmetry car:

Creating wind tunnel:

• for creating wind tunnel we have to go to top and then create a reffrence point below the car as shown below
• after that calculate the dimension of the wind tunnel and create the wind tunnel as shown below

Surface meshing of the wind tunnel:

• The top side element length is 100. The bottom side element length is 20. Use the option "Spacing" in paramter. Select geometry type. Enter dmin as 20 and dlmt as 100 and select the 4 vertical cons of winf tunnel.
• apply surface mesh on wind tunnel

Conclusion:

• The BMW car model is top-cleaned and has a suitably netted surface.
• A wind tunnel is created and the surface is meshed with reference to the size of the car model.
• There are different volumes of the car model because the shock absorber and tires are not connected to the car body.
• A single volume is created from the car body, so that it can be avoided in one go when creating a volume mesh.
• The required physical tests can be performed on the volume model of the wind tunnel after a successful volume connection.

link for meshed geometry:https://drive.google.com/file/d/1TrTjxj4FV1cHLqkcGuvjkCBzE45Fpsja/view?usp=sharing