[firedrake] Boundary conditions

[Cotter, Colin J]

Dear Firedrakers,
  I decided to create another set of cohomology tests, this time with Dirichlet boundary conditions, since there is a nice result relating the kernels of the operators with and without Dirichlet boundary conditions (for the maths-curious, it's Poincare duality).

  However, I can't get the boundary tags into Firedrake from gmsh. If I attempt to tag the boundary using "Physical Line" in gmsh (see bottom of this email for the .geo file), the line
>>mesh = Mesh("annulus.msh")
produces:
*** ERROR ***
Error message: Unsupported mixture of face/element types

Removing the physical line makes the error message go away, so there is something wrong with that line.

What have I done wrong?

all the best
--Colin

Point(1) = {0, 0, 0, 1.0};
Point(2) = {1, 0, 0, 1.0};
Point(3) = {1, 1, 0, 1.0};
Point(4) = {0, 1, 0, 1.0};
Point(5) = {0.3333333333333, 0.3333333333333, 0, 1.0};
Point(6) = {0.66666666666666, 0.3333333333333, 0, 1.0};
Point(7) = {0.66666666666666, 0.66666666666666, 0, 1.0};
Point(8) = {0.3333333333333, 0.66666666666666, 0, 1.0};
Line(1) = {1, 2};
Line(2) = {2, 3};
Line(3) = {3, 4};
Line(4) = {4, 1};
Line(5) = {5, 6};
Line(6) = {6, 7};
Line(7) = {7, 8};
Line(8) = {8, 5};
Line Loop(1) = {1, 2, 3, 4};
Line Loop(2) = {5, 6, 7, 8};
Plane Surface(1) = {1,2};
Physical Line(9) = {2, 3, 4, 1, 6, 7, 8, 5};

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