(Note... I started this email earlier this morning... but just now finished it and there are like 10 new emails in this thread so forgive me if I'm off-topic now)
On Nov 11, 2008, at 7:42 AM, Benjamin Kirk wrote: > If we had a C1 mapping element I'd think we could project the C0 > subdivision > surface into the C1 space... In fact, I think we would almost > always have > to do this with any mapping element other than Lagrange. (Does > anyone know > of a surface mesh format which specifies the coordinates in terms of > e.g. > Clough-Tocher basis weights?) At Sandia when we were doing higher order geometry on surfaces so that we could refine the mesh and "pop" to the higher order surface.... we had to invent our own "auxiliary" file that we read in with the mesh. That file defined the extra degrees of freedom per edge / node that described the higher order geometry (essentially tangents and normals). > It seems like using anything other than Lagrange would involve a > 'startup' > phase where we declare a system on top of lagrange-mapped FEs in the > usual > way, solve an L2 projection or something to get the geometry on the > desired > mapping basis, and then redefine the mesh somehow, probably with an > out-of-core write/restart file... But that's just a detail. This seems reasonable to me. > To keep the code anything resembling efficient, we'd need to make sure > multiple mapping types are supported at the same time... I'd think > we want > to use the C1 map *only* on elements with a face or edge trace on the > boundary of interest. Yes... this is exactly what we did at Sandia.... maintained higher order geometry representation on the boundary only. We had two different methods for getting that higher order geometry into the code. The simplest is that we could read a second order mesh generated from Cubit.... then essentially throw away all of the second order information on the interior and only keep the exterior elements as second order. The second was to postprocess a mesh from Cubit using a third party program (that came from Cubit) that would generate that auxiliary file with the descriptions of normals and tangents on the nodes / edges on the boundary... then we would use this information to "pop" new nodes to the "higher order" boundary when doing refinement. I hope any of that was relevant. Derek ------------------------------------------------------------------------- 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
