[Gmsh] Illegal tets message

[Steve Daley]

I am running GMSH to produce the tet mesh around a closed ended circular cylinder at 135 degrees angle of incidence to use in a CFD simulation.  I use a STL file to define the cylinder triangular surface. The outer boundary of the volume is a six faced box.

GMSH produces a tet mesh around the scylinder inside the box but outputs a message  "NN illegal tets are still in the mesh" where NN is a number depending on the number of triangles in the STL file.  How does GMSH decide a tet is an "illegal tet" ?

For other cases, GMSH also outputs the message "NN points could not be inserted". NN is again a number.  Is there any way to find out why there are problems with these points and where they are ?

For these, I can send you my STL and GEO files if that will help.

Finally, because I'm trying CFD mesh generation cases, I'm trying to limit the volume of the mesh to say one half of the body as the problem has a plane of symmetry.  I'm trying to use the Compound Line to define the geometry edge profile where the profile may be made up of 100 points.  Is there any restriction on the number of points that can make up a compound line ?   Even though its only a cylinder, I need that number of points to get the tets near to the surface to be quite small to resolve the flow solution.

Any help would be gratefully received.

Many thanks

Steve Daley
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