Hi @oscarcorripio,
thanks for your reply.
I checked the stp file different times with two different CAD tools (CATIA V5 and Geomagic Design X). I converted the file from .CatPart to .stp and read it back into the tools. Result in both tools was a 1 piece solid as it also written in the simscale geometry import check box. Below screenshots of both systems:
The material point is placed correct and far away from the geometry. It lies inside the BaseMeshBox. The refinement areas you see in the screenshots I did manual for the reason to get finer mesh in these regions, but in first step it is only necessary for the outside mesh.
Before I tried to mesh the current geometry I did run the same simulation with a much coarse dummy geometry without any problems.
The way you mentioned with the tunnel and subtracted solid is the way I will try as next. Maybe to work with a .stl file can be another step.
But in general the mesh result remains unclear for me.