Dear all,

I want to enforce DirichletBCs on an extruded mesh. For a normal unit cube tetrahedron mesh I could use the following face ID's:

1: x ==0

2: x==1

3: y==0

4: y==1

5: z==0

6: z==1

However, when I do the following:

meshbase = RectangleMesh(Nx, Ny, Lx, Ly, quadrilateral=True)

mesh = ExtrudedMesh(meshbase, Nz, Dz)

I get this error:

Traceback (most recent call last):
  File "VMS_patch_test_3D_Double_firedrake.py", line 51, in <module>
    FrontBackBC1 = DirichletBC(wSpace.sub(0).sub(1),Constant(0.0),(3,4))
  File "/data/Software/firedrake/src/firedrake/firedrake/bcs.py", line 68, in __init__
    raise NotImplementedError("Indexed VFS bcs not implemented on extruded meshes")
NotImplementedError: Indexed VFS bcs not implemented on extruded meshes

What should I do to properly identify my boundary faces?

 Regards,

Hanie