Overwriting m.coordinates doesn't change m's "ufl_cell", which remains Cell('interval', 2). This gets used during the extrusion process, leaving you with a mesh that thinks it's in 3 dimensions.

I'm also not sure why you're using Expression(("0.", "0.")) in the DirichletBC, since 0 will suffice.

On 11 November 2014 17:28, Shipton, Jemma <j.shipton@imperial.ac.uk> wrote:

Hello,

I'm trying to solve a problem that works on an extruded periodic interval mesh on an extruded circle mesh. I am getting the following error:

Traceback (most recent call last):
File "extruded_circle_helmholtz.py", line 57, in <module>
bcs = [DirichletBC(W[0], Expression(("0.", "0.")), "bottom"),
File "/home/jemma/src/firedrake/firedrake/bcs.py", line 56, in __init__
self.function_arg = g
File "/home/jemma/src/firedrake/firedrake/bcs.py", line 95, in function_arg
g = function.Function(self._function_space).interpolate(g)
File "/home/jemma/src/firedrake/firedrake/function.py", line 182, in interpolate
% (sum(dims), np.prod(expression.value_shape(), dtype=int)))
RuntimeError: Expression of length 3 required, got length 2

The problem appears to be that the mesh coordinates have 3 components whereas the extruded interval mesh coordinates only have 2. Any idea how to fix?

My code is here:

https://gist.github.com/anonymous/dff509883518ef0f5f2d

Thanks!

Jemma