David's right.... On Sep 27, 2008, at 11:26 AM, David Knezevic wrote:
> Well, the problem I think is that the gradients are not well-defined > at > node points, since finite element solutions are piecewise polynomials. Yep.. for your normal Lagrange elements the gradient is undefined on the element boundaries (including the nodes). Now, for C1 continuous elements (such as Clough-Toucher's, Hermite's, etc.) you should be able to get the value of the gradient at the nodes pretty easily: it should be in your solution vector. Obviously, I've never used these elements or I would know the answer to that... maybe Roy could fill us in. > One way to get an answer (John suggested this to me once) is to > compute > the gradients at quadrature points and then do an L2 projection of > that > solution, and then just sample the projected solution at the nodes. Yep... this is what's calle "Gradient Recovery". There are several methods for doing this... 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
