Meshing of multiple geometries with surface meshing for inner geometry and volume meshing for outer geometry treating inner geometry as wall

I would like to learn meshing of 2 CAD geometries. Say, I have a byke geometry which is enclosed in a rectangular tunnel. I want volume mesh for tunnel and the inner Byke should have surface meshing only. I mean the byke should not have volume meshing inside it. I would like to simulate the flow over the byke treating it as a WALL. Any suggetions or tutorials for this problem would be helpfull. I am new to this forum and this is my question. Thank you in advance.

you need to have two geometries, one for your tunnel, and the other one for the bike, then you will remove by using cut, the geometry of the bike to the tunnel, this will generate the volume you want to mesh, with the faces of your bike (and its volume removed). then you mesh this body. here is a simple example
example.hdf (128,7 KB)
and you can find some tutorials about salome so you get your hands on:

Dear Franco, Thank you for your response. I already followed the procedure you suggested. This is only working if both the geometries are created in Salome. In my work, I created tunnel in Salome and downloaded the Bike geometry from online. In this case, the cut option is not working showing Error. I tried to generate the solid from the bike and then used cut option. But still some error is encountered and operation is aborting. I hope I need to clean (repair) the downloaded geometry. I do not have any software to repair it, If you do have any suggestion on repairing geometry, please share. Thank you.

hello, it is not a matter of being generated in salome, it is a matter of the file type, I recommend that you learn the basic files types:
CAD: STEP/BREP (volumetric objects) IGES (volumetric surfaces)
surface mesh: STL/OBJ (discretized volumetric surfaces)
I imagine that in what you downloaded is a surface mesh, and thats why you are having problems.
if it is that case, I dont think salome is the correct tool for this (disclaimer I am a user of salome not a developper nor an expert, I simply try to help the community), I would recommend snappyHexMesh or cfMesh from OpenFOAM toolkit, not sure but maybe also gmsh has this kind of workflow also. If you insist in doing it in salome, you should create a body (CAD object) from your surface mesh, if you achieve to get a CAD file of your geometry the previous worflow would work by importing the geometry.