Gmsh 4.x does not export msh2 ghosted partitions correctly
Given small.geo, calling Gmsh 3.0.6 with:
gmsh small.geo -2 -nopopup -part 2 -format msh2 -o small_306.msh
produces small_306.msh, whereas calling Gmsh 4.4.1 with:
gmsh small.geo -2 -nopopup -part 2 -part_ghosts -format msh2 -o small_441.msh
In addition to the duplicate triangles, the partitions generated from Gmsh 4.4.1 are, e.g.,
1 -1 and
2 -2, so the ghosts sit on the same partitions as the "corporeal" cells. Gmsh 3.0.6 produces
1 -2 and
2 -1, as expected.
I'm aware that it says:
Warning : Saving a partitioned mesh in a format older than 4.0 may cause information loss
but this isn't information loss; it's just wrong. I'm also aware that this format is archaic, but it's presently the only one that FiPy understands (we're working on that, but other issues have taken precedence).
(Gmsh versions just the two that were readily available from conda-forge)