[petsc-users] DMPlex: Ghost points after DMRefine

[Morten Nobel-Jørgensen]

I have a very simple unstructured mesh composed of two triangles (four vertices) with one shared edge using a DMPlex:

 /|\
/ | \
\ | /
 \|/

After distributing this mesh to two processes, each process owns a triangle. However one process owns tree vertices, while the last vertex is owned by the other process.

The problem occurs after uniformly refining the dm. The mesh now looks like this:

 /|\
/\|/\
\/|\/
 \|/

The new center vertex is now not listed as a ghost vertex but instead exists as two individual points.

Is there any way that this new center vertex could be created as a ghost vertex during refinement?

Kind regards,
Morten

Ps. Here are some code snippets for getting global point index and test of point is a ghost point:


int localToGlobal(DM dm, PetscInt point){
    const PetscInt* array;
    ISLocalToGlobalMapping ltogm;
    DMGetLocalToGlobalMapping(dm,&ltogm);
    ISLocalToGlobalMappingGetIndices(ltogm, &array);
    PetscInt res = array[point];
    if (res < 0){ // if ghost
        res = -res +1;
    }
    return res;
}

bool isGhost(DM dm, PetscInt point){
    const PetscInt* array;
    ISLocalToGlobalMapping ltogm;
    DMGetLocalToGlobalMapping(dm,&ltogm);
    ISLocalToGlobalMappingGetIndices(ltogm, &array);
    return array[point]<0;
}
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