[Dune] GMSH reader fails in reading the same file for AlbertaGrid<2, 3> but not for ALUSimplexGrid<2, 3>

[Sacconi, Andrea]

Hi everyone,

I'm experiencing a problem, again, with the GMSH reader.

You will find attached two .msh files.

I managed to import a .msh file for a boundaryless surface (representing a sphere, an ellipsoid, ...) into ALUSimplexGrid<2, 3>, eliminating from the .msh all the elements that are not triangles (otherwise the segments would be interpreted as boundary objects, but here there is no boundary at all). Thanks to Andreas Dedner for the useful suggestion.

Anyway, if I try to use the same file with AlbertaGrid<2, 3>, this error message appears on my screen:

Loading macro grid: ../data/ellipsoid.msh
Reading 2d Gmsh grid...
version 2.2 Gmsh file detected
file contains 92 nodes
file contains 178 elements
number of real vertices = 91
number of boundary elements = 0
number of elements = 178
Error: GridError [setOrientation:macrodata.cc:259]: Surface grid cannot be oriented.

It seems that the same file gives problems with the orientation of the elements, but only in the AlbertaGrid case.
Here my questions:

1) are there any specific requirements about the orientation I should pay attention to? Check also the (long, sorry!) post scriptum.
2) why doesn't ALUGrid detect the problem?

Cheers,

Andrea
________________________

PS, if I try with another file, the problem doesn't appear. For example:

Loading macro grid: ../data/mesh_GMSH_coarse_new.msh
Reading 2d Gmsh grid...
version 2.2 Gmsh file detected
file contains 19 nodes
file contains 32 elements
number of real vertices = 18
number of boundary elements = 0
number of elements = 32
macro_test_2d:      WARNING in ./../2d/macro_2d.c, line 451
                    There is a cycle beginning in macro element 14.
                    Correcting refinement edges....
reorder_2d:         Current elem: 0, best_edges: 0 3 3
                    Current elem: 1, best_edges: 2 3 3
                    Current elem: 2, best_edges: 1 3 3
                    Current elem: 3, best_edges: 2 3 3
                    Current elem: 4, best_edges: 0 3 3
                    Current elem: 5, best_edges: 2 3 3
                    Current elem: 6, best_edges: 0 1 2
                    Looking at best_edges[6][0]...
                    Found compatibly divisible neighbour 7!
                    Current elem: 8, best_edges: 0 3 3
                    Current elem: 9, best_edges: 1 3 3
                    Current elem: 10, best_edges: 1 3 3
                    Current elem: 11, best_edges: 2 3 3
                    Current elem: 12, best_edges: 0 3 3
                    Current elem: 13, best_edges: 1 3 3
                    Current elem: 14, best_edges: 1 3 3
                    Current elem: 15, best_edges: 2 3 3
                    Current elem: 16, best_edges: 0 3 3
                    Current elem: 17, best_edges: 0 1 2
                    Looking at best_edges[17][0]...
                    Found compatibly divisible neighbour 19!
                    Current elem: 18, best_edges: 1 3 3
                    Current elem: 20, best_edges: 0 3 3
                    Current elem: 21, best_edges: 1 3 3
                    Current elem: 22, best_edges: 1 3 3
                    Current elem: 23, best_edges: 2 3 3
                    Current elem: 24, best_edges: 0 3 3
                    Current elem: 25, best_edges: 2 3 3
                    Current elem: 26, best_edges: 2 3 3
                    Current elem: 27, best_edges: 1 3 3
                    Current elem: 28, best_edges: 0 3 3
                    Current elem: 29, best_edges: 1 3 3
                    Current elem: 30, best_edges: 1 3 3
                    Current elem: 31, best_edges: 2 3 3
check_mesh:         checking mesh 'DUNE AlbertaGrid'
                    checking done; no error detected
Grid file read correctly.

__________________________________________________________

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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