k

firedrake/bcs.py

@@ -290,7 +290,7 @@ def __init__(self, V, g, sub_domain, method=None):
                 warnings.warn("Selecting a bcs method is deprecated. Only topological association is supported",
                               DeprecationWarning)
         if len(V.boundary_set) and sub_domain not in V.boundary_set:
-            raise ValueError(f"Sub-domain {sub_domain} not in the boundary set of the restricted space.")
+            raise ValueError(f"Sub-domain {sub_domain} not in the boundary set of the restricted space {V.boundary_set}.")
         super().__init__(V, sub_domain)
         if len(V) > 1:
             raise ValueError("Cannot apply boundary conditions on mixed spaces directly.\n"

tests/firedrake/regression/test_restricted_function_space.py

@@ -270,3 +270,16 @@ def test_restricted_function_space_extrusion():
         assert np.allclose(v.getArray(), local_array[:n][local_global_filter])
         v *= 2.
     assert np.allclose(f.dat.data_ro_with_halos[:n][local_global_filter], 2. * local_array[:n][local_global_filter])
+    # Solve Poisson problem.
+    x, y = SpatialCoordinate(extm)
+    normal = FacetNormal(extm)
+    exact = Function(V_res).interpolate(x**2 * y**2)
+    exact_grad = as_vector([2 * x * y**2, 2 * x**2 * y])
+    u = TrialFunction(V_res)
+    v = TestFunction(V_res)
+    a = inner(grad(u), grad(v)) * dx
+    L = inner(-2 * (x**2 + y**2), v) * dx + inner(dot(exact_grad, normal), v) * ds_v(2) + inner(dot(exact_grad, normal), v) * ds_t
+    bc = DirichletBC(V_res, 0., "bottom")
+    sol = Function(V_res)
+    solve(a == L, sol, bcs=[bc])
+    assert assemble(inner(sol - exact, sol - exact) * dx) ** 0.5 < 1.e-14