On Mon, 12 Feb 2018, Manav Bhatia wrote:
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So, would the shape function derivatives account the orientation of the element? For instance, a 1D element oriented along: x-axis vs y-axis vs x=y line. In all cases, there is only one shape function defined along the element coordinate. But its derivative wrt x and y will vary. Is this handled for both 1st order and 2nd order Lagrange (for instance)?
IIRC it's handled properly for all scalar-valued elements, where by "properly" I mean that the derivative is returned as a directional gradient in LIBMESH_DIM-dimensional space. E.g. If you have an EDGE2 element with a value of 1 at the origin and 0 at the other end, then if the other end is at (x,y,z) the gradient in physical space we return should be (-x, -y, -z). That means that if you're solving e.g. a Laplacian problem, then you want to be integrating grad(u)*grad(v) as a dot product of 2 vectors, not just assuming that you can still ignore the m>>n indexed components for an n-dimensional element. I'm actually not sure if anybody ever made sure we support embedded vector-valued elements. Cc'ing Paul Bauman; if he didn't do it then nobody did. --- Roy ------------------------------------------------------------------------------ Check out the vibrant tech community on one of the world's most engaging tech sites, Slashdot.org! http://sdm.link/slashdot _______________________________________________ Libmesh-users mailing list Libmesh-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/libmesh-users
