On Fri, 19 Feb 2010, Karen Lee wrote: > const Real value = exact_solution(xf, yf); > > is the line that gives the value, so if I wanted to impose that the > values at the boundary are 0, I just put 0 instead right?
Right. In fact, in a linear system like ex3 the whole residual drops out in this case, and homogeneous Dirichlet boundaries only end up affecting your matrix. For nonlinear systems things are trickier depending on your solver; see ex18 for an example. > The other thing is, I'm not sure whether BoundaryMesh can just locate > the boundary. I use tetgen .node and .ele files, and it > doesn't seem that the .face files are read by libmesh, and so I'm > wondering how it's able to locate the boundary... Or do I add > some tags and say that certain nodes and elements are on the boundary? The boundary is currently implicitly defined: if an element doesn't have a neighbor on one side, that side is a boundary side. If a node is on a boundary side, that node is a boundary node. That works fine for most domains, which are the interior of their own closure. If you've got something more complicated, let us know, but don't be too optimistic. We currently break when refining domains with infinitely thin slits, for one embarrassing example. --- Roy ------------------------------------------------------------------------------ Download Intel® Parallel Studio Eval Try the new software tools for yourself. Speed compiling, find bugs proactively, and fine-tune applications for parallel performance. See why Intel Parallel Studio got high marks during beta. http://p.sf.net/sfu/intel-sw-dev _______________________________________________ Libmesh-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/libmesh-users
