Issues visualizing multiple fields stored in single XDMF file [dolfinx]

[dokken]

1. If you same multiple fields to the same mesh, you need to use extract block to extract each field.

2. In can reproduce this, but I do not think it is an issue of DOLFINx, rather a limitation of Paraview.

In general, xdmf is going to be phased out, so I would suggest switching to VTXWriter (ADIOS2 based), as it does what you want to do:

with io.VTXWriter(MPI.COMM_WORLD, "test.bp", [u,v]) as xf:
    xf.write(0.0)