On Tue, Jan 15, 2008 at 12:42:29AM +0100, Murtazo Nazarov wrote: > > On Tue, Jan 15, 2008 at 12:23:30AM +0100, Murtazo Nazarov wrote: > >> > On Mon, Jan 14, 2008 at 08:57:34PM +0100, Murtazo Nazarov wrote: > >> >> > Is there an obvious high level way to implement normal flow type > >> >> > boundary conditions or symmetry type boundary conditions? > >> >> > > >> >> > -gideon > >> >> > > >> >> > >> >> If you mean slip boundary condition which for normal velocity, it is > >> >> already implemented and soon will be available with UNICORN. > >> >> > >> >> The slip with friction is also implemented. > >> >> > >> >> /murtazo > >> > > >> > How is this implemented and for which element types? Maybe it can be > >> > added to DOLFIN. > >> > > >> > >> It is implemented in the "stong" way as the Dirichlet BC. The idea is to > >> put u*n = u1*n1 + u2*n2 + u3*n3 = 0, where u = (u1,u2,u3) velocity and n > >> = > >> (n1,n2,n3) normal to a boundary node. At the monent it works for simple > >> (cylinder, cube, ...) and quite complex geometries (car), but we are > >> testing it in different geometries. Then, it would be good to add it to > >> DOLFIN. > > > > I mean how do you translate u1*n1 + u2*n2 + u3*n3 = 0 into an equation > > for the degrees of freedom (which may or may not be u1, u2, u3), which > > types of finite elements does this work for and how do you modify the > > linear system? > > > > It is done for the linear system. The idea is almost the same as Dirichlet > implementation, but here we change two (in 2D), three (in 3D) > corresponding rows of the system.
ok, but how exactly do you make the modification? > I think (I may be wrong) it has nothing to do with the types of > finite elements. ok, but some more information about how it's done would be good (since this would be a good feature to add). -- Anders _______________________________________________ DOLFIN-dev mailing list [email protected] http://www.fenics.org/mailman/listinfo/dolfin-dev
