Element type mixtures not allowed?

mesh
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1

My noob random walk in the world of FEniCS/dolfinx has recently allowed me to generate 2D meshes with gmsh, which I then import with dolfinx.io.gmshio.read_from_mesh.I have even managed to get PyVista up and running inside my jupyter notebook.

However, when I recently tried to use a 2D mesh with a mixture of (2nd order) tri and quad elements, read_from_mesh stopped and complained. The code comment at the point of the assert(in gmshio.py), states that “Assumes that each entity only have one cell-type“.

So, is it just read_from_mesh which cannot handle this, or is this a limitation of, say, the implementation of the function spaces? That is, can I hope for a workaround, or should I keep my paws away from mixed meshes?

2

The GMSH interface does not support reading in mixed cell meshes (yet). There is experimental support for these meshes in DOLFINx, see for instance: Poisson equation — DOLFINx 0.10.0.post0 documentation
but the API is subject to change and is not super-clean at the moment.