Great - that's exactly what I needed! Thanks John!
Derek On Thu, Jun 12, 2008 at 3:48 PM, John Peterson <[EMAIL PROTECTED]> wrote: > On Thu, Jun 12, 2008 at 4:33 PM, Derek Gaston <[EMAIL PROTECTED]> wrote: >> Right - maybe I should think about these things before I say them ;-) >> >> So now the question is... if you were in my place and wanted to set a >> u-bc_val type residual for boundary elements... what would you do for >> tri's and tets? It seems like a post-processing step is the best way >> (so that something from an element with only a node on the boundary >> doesn't have a chance to contribute anything). What would that >> post-processing step be? Are there any facilities already in libMesh >> that could help out? >> >> I mean, I can certainly loop over the local_active_elements and add >> all the nodes on the boundaries to a std::vector<Node *> right after I >> read the mesh... but there is a bit of a problem with adaptivity in >> this case... and it feels hackish. But I suppose I was hoping that >> this is what a BoundaryMesh was... so I guess it's not all that much >> different. > > BoundaryInfo::build_node_list() does what you suggest. Given the > current capabilities of the library, I'd say rebuilding this list > after each assembly, and going through and modifying those entries in > the residual vector is the way to do it. This should also be done in > parallel, i.e. you only set the dof indexes from these nodes which are > on your processor. > > -J > > > > >> >> Thanks, >> Derek >> >> On Thu, Jun 12, 2008 at 3:25 PM, Benjamin Kirk <[EMAIL PROTECTED]> wrote: >>>> So how are other people doing boundary conditions with tri's and >>>> tets? With Dirichlet you can just use a penalty to swamp everything >>>> out. But with Nuemann? >>> >>> Neumann is not an issue because the BC is in terms of the boundary integral, >>> so you only consider it with elements whose sides intersect the boundary. >>> The elements who only touch the boundary through a node do not enter into >>> the Neumann BC. >>> >>> >> > ------------------------------------------------------------------------- Check out the new SourceForge.net Marketplace. It's the best place to buy or sell services for just about anything Open Source. http://sourceforge.net/services/buy/index.php _______________________________________________ Libmesh-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/libmesh-users
