Setting initial condition on irregular boundary from marked input mesh

General
2

Use a Dirichlet bc to set values on that particular boundary.

left_dofs = dolfinx.fem.locate_dofs_topological(V, domain.topology.dim-1, left_facets)
init_value=0.
bc_init= dolfinx.fem.dirichletbc(init_value, left_dofs, V)
dolfinx.fem.petsc.set_bc(u.vector, [bc_init])