How to set up a function space consisting of multiple domains from an imported gmsh mesh for an elasticity analysis

[dokken]

@prusso630

Q = FunctionSpace(mesh, ("DG", 1))



E = Function(Q)
mu_indices = np.where(cell_markers.values == 11)[0]
lambda_indices = np.where(cell_markers.values == 12)[0]
E.x.array[mu_indices] = np.full_like(mu_indices, 200, dtype=ScalarType)
E.x.array[lambda_indices] = np.full_like(lambda_indices, 500, dtype=ScalarType)

You are assuming a 1 to 1 relationship between the dofs of a DG-1 space and the cell indices. This is not correct, as there is only a 1-1 relationship between a DG-0 space and the cell indices. So i would suggest using a DG-0 space.

See also part two of the tutorial: Defining subdomains for different materials — FEniCSx tutorial
which creates materials based on cell data from the mesh markers.