Best strategy for importing external meshes

[dokken]

I have shown how to import meshes from gmsh using meshio in:

Transitioning from mesh.xml to mesh.xdmf, from dolfin-convert to meshio

As far as I can tell you would like to have a 3D mesh (tetrahedrons). Then you also need to mark the volumes: // Gmsh project created on Tue May 18 16:34:55 2021 SetFactory("OpenCASCADE"); //+ Circle(1) = {0, 00, 00, 0.6, 0, 2*Pi}; //+ Circle(2) = {0, 00, 00, 0.4, 0, 2*Pi}; //+ Curve Loop(1) = {1}; //+ Curve Loop(2) = {2}; //+ Plane Surface(1) = {1, 2}; //+ Extrude {0, 0, 10} { Curve{2}; Curve{1}; Layers {1}; Recombine; } //+ Curve Loop(5) = {6}; //+ Curve Loop(6) = {4}; //+ Plane Surface(4) …