Yes, what Lawrence says is correct. Hopefully the PR will be merged soon. Thanks. 2015-10-02 13:46 GMT+01:00 Mitchell, Lawrence < lawrence.mitchell@imperial.ac.uk>:

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On 2 Oct 2015, at 13:10, Stephan Kramer <s.kramer@imperial.ac.uk> wrote:

Hey guys

I've been trying to implement a simple IP viscosity scheme for DG, but was getting weird results, which I think I've tracked down to a bug related to fd_bendy.

If I run the following:

from firedrake import *

mesh2d = UnitSquareMesh(1,1) V = VectorFunctionSpace(mesh2d, "DG", 1) uv = Function(V) U_test = TestFunction(V)

n = FacetNormal(mesh2d) F1 = dot(jump(U_test[0], n), jump(uv[0], n))*dS F2 = -dot(avg(grad(U_test[0])), jump(uv[0], n))*dS F=F1+F2 F0 = dot(jump(U_test[0],n)-avg(grad(U_test[0])), jump(uv[0], n))*dS

M=assemble(derivative(F, uv)).M.values M1=assemble(derivative(F1, uv)).M.values M2=assemble(derivative(F2, uv)).M.values M0=assemble(derivative(F0, uv)).M.values

Do you mind wrapping this up as a test (to merge against current master) that ensures we don't regress when merging bendy?

Lawrence