Hi @jpdean, I have been trying to run your script buoyancy_driven_flow.py with the docker image dolfinx/dolfinx:v0.9.0. Is it not working, or are you using a different version of the code?
I’ve been trying to do this
# create mesh and submesh above...
V1 = dolfinx.fem.functionspace(mesh, ("Lagrange", 1))
V2 = dolfinx.fem.functionspace(submesh, ("Lagrange", 1))
W = ufl.MixedFunctionSpace(V1, V2)
wh = dolfinx.fem.Function(W)
# solve nonlinear problem
and am looking for a workaround. Looks like the same error occurs in this post: Applying ufl.action when using ufl.MixedFunctionSpace