18 Feb
2016
18 Feb
'16
11:08 a.m.
On 18/02/16 11:01, William Booker wrote:
Dear all,
Hopefully this will help provide a bit more context for the problem.
OK, so you have a space (L^2)^3 on which you would like to impose u.n=0 on the boundary of the domain. As David says, in general, we can't lift the appropriate boundary nodes because the vector field normal to the boundary does not correspond to particular degrees of freedom. Can you instead enforce your boundary condition weakly, by requiring that \int u.n ds vanishes? In general in fully discontinuous spaces, it makes more sense to impose the boundary conditions weakly rather than strongly (after all, none of the nodes are topologically associated with the boundary anyway). Cheers, Lawrence