[petsc-users] DMPlexCreateFromDAG for P2 elements

[Asitav Mishra]

Hi,

Does Petsc support DMPlexCreateFromDAG for 2nd order (P2) elements, or any
orders higher than one (P1) for that matter? I know it is possible to
create DMPlex mesh from GMSH files with P2 elements, but not sure how the
'cone/support' structures are built. One approach is to ignore the higher
order nodes in an element to create the 'cones', but is there a way to
preserve the P2 element information in the 'cones'?

For example: how would the depth=1 cone structure look like for a mesh with
two P2 triangles sharing a face?
            2
          / | \
        /   |   \
     6     |     8
    /       |       \
  /         |         \
0   0    5    1    3
  \         |         /
    \       |       /
     4     |     7
        \   |   /
          \ | /
           1

Higher order nodes: [4, 5, 6, 7, 8]. Can we construct cones with
cells-to-nodes (depth = 1)?:

numPoints = [9, 2];                                             // 9 nodes
instead of just 4?
coneSizes = [6, 6,    0, 0, 0, 0, 0, 0, 0, 0, 0];
cones        = [0, 1, 2, 4, 5, 6,    2, 1, 3, 5, 7, 8];
etc.

Any help would be greatly appreciated.

Thanks,
Asitav

-- 
Asitav Mishra, PhD
Research Engineer II, NIA
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