Hi,
I often use CAD-generated geometries (e.g. from Solidworks), which are exported to STEP format. To calculate the mesh I used gmsh. But gmsh has the problem that for adjacent bodies having each their own outer surface, the mesh nodes did not match at the interface, so not heat or current can flow between the bodies. I want to share information on some workarounds for this problem.
One partial solution is to use the same mesh width at both sides of the interface, and then use the merge option of Elmergrid to merge the nodes. But this does only work if for ALL interfaces the width is the same.
Another solution could be to mesh the geometry in Elmergrid directly, as Elmergrid can read STEP format. I have tried this for a test geometry in 2D and got an absolutely unusable result.
It seems that Salomé does not have this problem. But I have to use Windoze, and the Salomé Version for Windoze is said to be experimental. Moreover, Salomé seems to be not that easy to use. So I preferred to look for another possibility.
A workaround which I have found is to use netgen. Netgen can import the STEP file and "heal" it with a feature called "IGES/STEP Topology Explorer/Doctor". This "healing" seems to remove the duplicate interfaces. After that the geometry can be meshed with netgen directly, saved in gmsh *.msh format and imported in Elmer. Since I have not succeeded yet to get netgen to refine the mesh the way I need it, I save the "healed" geometry in STEP format (extension *.stp) and import that one in gmsh. This sounds cumbersome, but is done with only a few mouseclicks in netgen. In gmsh I can set the mesh width as I wish, do the meshing and get a mesh which does not have the double interfaces problem.
I hope this information will be useful for others.
Matthias