FEniCS, pygmsh and boundary conditions

[dokken]

As you are using OpenCascade, and not the built in geometry in gmsh, the functionality of pygmsh is slightly reduced.
What you need to add in add_raw_code is the raw gmsh code describing the tags. In your case:

geom.add_raw_code("Physical Surface(1) = { 1 };")
geom.add_raw_code("Physical Surface(2) = {2,3,4,5,6,7};")

I found these surfaces by visual inspection in gmsh by writing the original geometry to file by:

pygmsh.generate_mesh(geom, geo_filename="mesh.geo")

To answer your second question, this is covered in:

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

With all this code, I’m not really sure what you are asking for. Especially since you do not supply any error message. However, with the following modifications to the meshio and loading to dolfin code everything seems to run smoothly. (note that i’ve renamed the input mesh to meshi.read) import meshio msh = meshio.read("mesh.msh") for key in msh.cell_data_dict["gmsh:physical"].keys(): if key == "triangle": triangle_data = msh.cell_data_dict["gmsh:physical"][key] elif key == "te…