On Sat, 12 Sep 2009, David Knezevic wrote: > Ted Kord wrote:
>> How do I apply a Neumann B.C at an inter-element boundary? > > The same way as a usual Neumann BC... the only trick is that you have to > find which internal element to apply it to. One way to do this would be > to set the subdomain_id of elements on one side of the inter-element > boundary to 1 and on the other side to 2, and then search for elements > with subdomain_id = 1 that have a neighbor with subdomain_id = 2, and > apply the Neumann BC to the appropriate side of those elements. The trouble with this is that you'll still have the entries in your matrix from the shape functions which stretch between the element on one side of the boundary and on the other. If you have a slit in your domain on which you want to weakly impose boundary conditions, you need to make it an actual topologically broken slit, and then it's just another set of exterior boundaries. IIRC there used to be a bug with libMesh's find_neighbors() reconstruction that would undesirably "patch up" infinitely thin slits. I don't recall whether I fixed that or whether I just worked around the problem by making the slit 1e-6 wide... --- Roy ------------------------------------------------------------------------------ Let Crystal Reports handle the reporting - Free Crystal Reports 2008 30-Day trial. Simplify your report design, integration and deployment - and focus on what you do best, core application coding. Discover what's new with Crystal Reports now. http://p.sf.net/sfu/bobj-july _______________________________________________ Libmesh-users mailing list Libmesh-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/libmesh-users
