[Dune] DGF format and local ordering of vertices

[Sacconi, Andrea]

Hi everyone,

I'd like to ask you a question about the Dune Grid Format (DGF) and the ordering of the corners in an element of the mesh.

Suppose I put my vertices and my simplices in a dgf file, and then I use it to feed the grid constructor (Alberta, ALUGRID, whatever).
In the online documentation about the DGF, under the field "Simplex", I read that "no ordering of local vertices is required".
In my particular case, however, I do need a special ordering, since I'm dealing with hypersurfaces. To set an example: if you have the unit cube as initial geometry, I need that, looking from outside, all the triangles have corners counter-clockwise oriented s.t. the unit normal points outward.  I do need that this ordering (used in .dgf file) is preserved!

Is there any way of knowing whether this important information is preserved? Otherwise, the computation of the normal to each triangle could lead to weird results (strong nonsymmetric time-dependent behaviour for initial symmetric configurations).

Thanks for your help!

Andrea
__________________________________________________________

Andrea Sacconi
PhD student, Applied Mathematics
AMMP Section, Department of Mathematics, Imperial College London,
London SW7 2AZ, UK
a.sacconi11 at imperial.ac.uk
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