cashocs.io.mesh.import_mesh#

cashocs.io.mesh.import_mesh(mesh_file: str, comm: MPI.Comm | None = None) → _typing.MeshTuple[source]#

Imports a mesh file for use with cashocs / FEniCS.

This function imports a mesh file. The mesh file can either be a Gmsh mesh file or an xdmf mesh file that was generated by GMSH and converted to .xdmf with the function cashocs.convert(). If there are Physical quantities specified in the GMSH file, these are imported to the subdomains and boundaries output of this function and can also be directly accessed via the measures, e.g., with dx(1), ds(1), etc.

Parameters:

  • mesh_file (str) – The location of the mesh file in .xdmf or .msh file format.

  • comm (MPI.Comm | None) – MPI communicator that is to be used for creating the mesh.

Returns:

A tuple (mesh, subdomains, boundaries, dx, ds, dS), where mesh is the imported FEM mesh, subdomains is a mesh function for the subdomains, boundaries is a mesh function for the boundaries, dx is a volume measure, ds is a surface measure, and dS is a measure for the interior facets.

Return type:

_typing.MeshTuple

Notes

In case the boundaries in the Gmsh .msh file are not only marked with numbers (as physical groups), but also with names (i.e. strings), these strings can be used with the integration measures dx and ds returned by this method. E.g., if one specified the following in a 2D Gmsh .geo file

Physical Surface("domain", 1) = {i,j,k};

where i,j,k are representative for some integers, then this can be used in the measure dx (as we are 2D) as follows. The command

dx(1)

is completely equivalent to

dx("domain")

and both can be used interchangeably.

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