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djoul January 16, 2012 16:04

Hybrid meshing ICEM
Hi eevryone,

It has been a couple of days/weeks I tried to figure out how to handle hybrid meshing in ICEM. It does not seem so obvious to me if even possible for some kind of geometry.
I want to connect a hex mesh from the block/hexa mesher to a fully (hex-dominant) unstructured grid. I have been through all kind of tutorials/forums discussion but cannot find a solution.

First I should warn about the "free" meshing in the block mesher, which will make the software crash half of the time. Another annoying point is that once you select one block to be free, you cannot reverse the process (specifying it mapped) for some unknown errors.
Anyway, going through all those problems, I finally end up having my hexa mesh built (3D, mostly hexa, prism in some swept part). The next step is to build the last part, fully unstructured. I therefore have to start from an existing shell interface mesh (mostly quads).
Doing tetra + 12:1 hexa does not work as the resulting surface mesh does not coincide any more with the initial one. The hexa dominant mesher does not work even if the surface mesh is defined everywhere. The prism mesher does not want to do it either for some mysterious "stuck triangles".

To sum up, I will be happy to know if there is one way to do this (meshing from an existing quad surface mesh) in ICEM. I am not used to mesh generation but this does not seem to me to be a crazy task for a meshing-tool.

Thanks for your help!

PS: I am using icem 13.0

PSYMN January 17, 2012 18:40

The Hex Dominant mesher (which I hope you are not using for CFD) can mesh from a quad dominant surface mesh, but it is picky.

It requires that the volume be closed, I don't think it can handle baffles or single edges and it requires enough room while meshing to fit relatively uniform (Isotropic) hexas). It also assumes that (since it is an FEA Mesher) the Hexas will be relatively equal in size. It doesn't handle large transitions well.

Not all the meshers play well together because some do not provide good starting points for others... I could give more specifics if you posted a pic of the issue.

djoul January 17, 2012 19:18

2 Attachment(s)
Hi Psymn

Thank you very much for your answer.
Attached is my geometry. This is the part where I don't really care too much. I just want it to be filled with hex/tet and plug the obtained mesh to my hexa mesh (not shown here).
So, my main constraint is to match this (mainly quad) surface mesh lying at the interface and already set by the hexa mesh.
I agree about using the tet mesher, but the first thing it does is converting all my quads to triangle... I think a layer of prism should do the trick but for some reasons it does not want to mesh it.

Thanks again.


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