On Tue, Jul 22, 2008 at 10:08:20PM +0200, Harish Narayanan wrote: > Is it possible to project a known field onto a different > (heterogeneously refined) mesh? I am trying to implement an adaptive > mesh refinement scheme which, in a given iteration, requires values of > fields from previous iterations which live on coarser meshes. > > I've been searching through this list's archives on my mail client, and > I stumbled upon two threads (from '06 and '07) that discuss the same > issue, but I am not sure if they resulted in a solution. > > Harish
No, it has not been implemented yet but it's something we desperately need. If we define the L2 projection Pu of u onto V by (Pu, v) = (u, v) for all v in V then the problem is in evaluating the integral on the right-hand side: (u, v) where now u and v are defined on different meshes. My suggestion would be to evaluate this by quadrature at run-time, using the generated UFC function evaluate_basis and IntersectionDetector/GTS which is very fast at finding the overlap between cells. A new function project() could be added to take care of this. There is already such a function in the Python interface (which handles projections on the same mesh) so that needs to be considered at some point. -- Anders
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