On Wed, 12 Nov 2008, Vijay S. Mahadevan wrote: > I am curious on the concept of the 'view' of a mesh.
Basically, we store hierarchic meshes like this: *-----------*-----------* *-----*=====*=====*=====* *==*==* Where the mesh is 1D, there are 5 active elements and 3 ancestor elements. We can also store meshes like this: *-----------*===========* *=====*=====*.....*.....* *..*..* Where there are 3 active elements, 1 ancestor element, and 4 "subactive" elements". Looping over active elements just gets you the ones in the active view, but the subactive elements and their associated Dof objects still exist. We use this for coarsening non-Lagrange elements properly, but it could make geometric multigrid possible too. > For example when I have an unstructured grid, and when I coarsen > uniformly twice and refine uniformly twice, would I get the exact > same mesh?! No. For instance, the second mesh above is a uniform coarsening (so far as such a thing exists) of the first mesh, but uniformly refining it will produce two new elements that weren't in the first mesh. We could, however, create a "rerefine" method that jumps you straight back to the finest mesh by making any active element with children into an ancestor and making any subactive element without children active. > If the dof_map and mesh can provide views that are consistent with > the refinement or coarsening based on an initial mesh, then I do think > this should be possible without too much programming effort for an > external user. Ideally the external user shouldn't need to do anything that he isn't already other than set some solver options or choose a different solver object. But that implies the existence of an internal developer with the time and expertise to do the library work, and such a person may not exist right now. > Of course, you would also have to propagate the mesh_data (Or again, > am I the only one using this ?) which stores material > information/element or create a view of it also. You may be the only one using this. ;-) But yes, we'd want to handle its restriction as well. --- Roy ------------------------------------------------------------------------- This SF.Net email is sponsored by the Moblin Your Move Developer's challenge Build the coolest Linux based applications with Moblin SDK & win great prizes Grand prize is a trip for two to an Open Source event anywhere in the world http://moblin-contest.org/redirect.php?banner_id=100&url=/ _______________________________________________ Libmesh-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/libmesh-users
