> energy). In order to approximate the fourth derivative, I either need an > H^2 conforming finite element or a DG element that is H^1. Is there any > such element implemented in the libraries of deal.II? > > But there seems not have an answer to it. why? and can anyone > give the answer to it?
The implementation of such elements is, at best, awkward. There are two options: - you can use a mixed formulation, by introducing a variable v and solving the system du/dt - beta Delta v = f v - Delta u = 0 - you can use one of the usual H^1 elements and add penalty terms to enforce H^2 continuity in the limit, in the same way as you use L^2 (discontinuous) elements and add penalty terms to enforce (H^1) continuity. Best W. ------------------------------------------------------------------------- Wolfgang Bangerth email: [email protected] www: http://www.math.tamu.edu/~bangerth/ _______________________________________________ dealii mailing list http://poisson.dealii.org/mailman/listinfo/dealii
