Can't get information about domains from mesh file

Netgen
1

Hello, everyone. For my calculation I have to get file in .xml format from my mesh, for this purpose I use Dolfin-convert. For creating mesh I use Netgen. My sample is simple and looks like this
`algebraic3d

solid cube1 = plane (0,0,0;-1,0,0 )
and plane (1,1,1; 1,0,0 )
and plane (0,0,0; 0,-1,0)
and plane (1,1,1; 0, 1,0 )
and plane (0,0,0.3; 0,0,-1 )
and plane (1,1,1; 0,0, 1 );

solid cube2 = plane (0,0,0; -1,0,0 )
and plane (1,1,1; 1,0,0 )
and plane (0,0,0; 0,-1,0 )
and plane (1,1,1; 0, 1,0 )
and plane (0,0,1.1; 0,0,-1 )
and plane (1,1,2.1; 0,0, 1 );

solid cube3 = plane (0,0,0; -1,0,0 )
and plane (1,1,1; 1,0,0 )
and plane (0,0,0; 0,-1,0 )
and plane (1,1,1; 0, 1,0 )
and plane (0,0,1.0; 0,0,-1 )
and plane (1,1,1.1; 0,0, 1 ) -maxh=0.05;

tlo cube3;
tlo cube1;
tlo cube2;`
I’m getting mesh, but in my .xml file I don’t have information about domains, I have only:
mesh celltype=“tetrahedron” dim=“3”
cells size=“18584”
tetrahedron index=“” v0=“” v1=“” v2=“” v3=“”
mesh_function type=“uint” dim=“2” size=“37838
entity index=”" value=“”
mesh_function type=“uint” dim=“3” size=“18584
entity index=”" value=“”.
When I ask about it in Dolfin community they told that it’s problem in mesh. Could you help me to get why it doesn’t give information about domains? Thanks.

2

first, you may want to name your faces ( with .bc(“name1”) ) and materials ( with .mat(“material3”) ).

The dolfin - export was an external contribution to Netgen long time ago, and looks like it does not care about region names, see:

Playing the ball back to the fenics/dolfin community, maybe someone from them could help putting the region labels into the right places.

Or you go via meshio to convert a Netgen mesh to Dolfin.

Joachim