METIS_MeshToDual vs. ParMETIS_V3_Mesh2Dual

[hheinzer]

There is a functional difference between METIS_MeshToDual and ParMETIS_V3_Mesh2Dual in the ncommon/ncommonnodes argument. The METIS function also places an edge, if the number of shared nodes is smaller than the total nodes of either element, minus one. Is there a simple way to force the METIS version to stick to the ncommon argument? For some of my meshes, erroneous connections are created due to this.

For context, I am working with 3D unstructured meshes, where the ghost cells are also tracked as cells, just with lower dimensionality. For hexahedral meshes, everything works as expected, as the ghost cells are quadrilaterals, which share only two nodes, so no edge is created between them (ncommon = 3). However, with tetrahedral meshes, the ghost cells are triangles and two adjacent triangles still share two nodes. Because of the connection condition min(ncommon, n1 − 1, n2 − 1), there will now be an edge between the two ghost cells. This connection is erroneous in the context of my program.