From: Roy S. <roy...@ic...> - 2007-07-05 13:01:19
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On Thu, 5 Jul 2007, Tahar Amari wrote: > Excuse me I may not be familiar with the terminology. The mistakes may be mine; I know roughly how the finite volume method works but I've never implemented it or studied it in much detail. >> For finite volume schemes where the volumes are the primal triangles, >> tetrahedra, etc. that libMesh supports, you can use one of our >> discontinuous finite element spaces like MONOMIAL or XYZ, and >> initialize the FE objects on interiors to calculate volume integrals >> and on element sides to handle flux integrals. > > Do you mean, Tetrahedral mesh with cell centered unknowns ? Yes, exactly. (or triangle mesh with cell centered unknowns, hex mesh with cell centered unknowns, etc.) >> For finite volume schemes where the volumes are centered on primal >> nodes and discontinuous on primal element interiors, I don't think >> there's an easy way to perform such calculations in libMesh. > > Do you mean, Dual mesh of the Tetrahedral mesh ? > In this case with node centered unknowns ? Again, that is correct. >> We'd appreciate your contribution, since a Tet14 class would be >> useful for high polynomial degree Hierarchic elements as well, but >> I warn you that it wouldn't be a simple task. > > I was thinking of Tet4, only four degree of freedom, on the faces. Yes, but because of the way libMesh uses the Node class for both degree of freedom storage and mesh geometry, a tetrahedron with only four face nodes can't be used to create a continuous mesh; at the very least you would additionally need four vertex nodes to define the geometry, even though with your FE class these nodes would hold zero degrees of freedom each. And although your application only needs 8 nodes, if you're going to all that effort then you might as well add the extra 6 edge nodes and give us a topologically complete element. ;-) --- Roy |