On Tue, 30 Oct 2018, Hubert Weissmann wrote:
> I must admit that I didn't look closely at the current implementation; I > just saw that the elements I would like to use are not done, so far. > Is there a strict reason why the elements must align with the axes? Alignment with the axes isn't strictly required, but alignment of edges approaching from opposite sides of a node is. So you could get parallelograms or something marginally better, but you'll never have a node of valence 3. > I have smooth parameters and driving forces, but my elements are > rather arbitrary and roughly align in spheres. That's what I was afraid of. > There are people who actually use InfFE with a 'rectangular' > interface, but I would actually like to avoid it... > Are the Clough-elements more promising? Well, they let you use arbitrary domains in 2D, but the mid-edge degrees of freedom cost you - if you subdivide quads to 2 Clough-Tocher triangles each, then Clough-Tocher gives you roughly 6 DoFs per quad, as opposed to 4 for Hermite or 9 for cubic Lagrange. More importantly, now the integration itself is going to cost you: each of those 2-macrotriangle quads has 6 subtriangles in it, and if you use the simple clough-tocher quadrature I did of slapping Gaussian points on each subtriangle then you're doing roughly 10 times as many point evaluations. This can still be worth it if the alternative would have involved a mixed method (18 DoFs for cubic Lagrange and more complexity at every quadrature point) but I don't think it's worth it just because you have a smooth solution. How big are your elements? Can you just use fewer elements with higher p (Hierarchics)? That will still leave you with lower smoothness so if you directly need smoothness it's not an option but if you're just trying to reduce the problem size for a given accuracy then that'd be the first thing I'd try. --- Roy _______________________________________________ Libmesh-users mailing list Libmesh-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/libmesh-users
