When I load a mesh from gmsh into a DM object, and not interpolate it, in
3D I only get the nodes and the tetrahedral elements. However, I'd also
like to retain the faces that I've put under a physical group that contain
the boundary conditions.
As I understand it, in the function DMPlexCreateGmsh, the faces are labeled
by looking for the join of the nodes they contain, which only exists if the
mesh is interpolated.
Is there a way to have faces that point to nodes, and tetrahedrals that
also directly point to nodes in the same mesh? I was able to hack it in by
changing DMPlexCreateGmsh, but then I run into trouble during the
distribution, as that is cell based I believe.
The reason I don't want to interpolate the mesh is because the mesh can be
very large, while the boundary conditions only apply to a very small
portion, so it would be a waste fully interpolating the mesh.