Vertex map from a SubMesh back to parent Mesh.

Question

I have a 3D simulation, running in parallel, with a Mesh that evolves over time. I need to extract the surface of the problem as a 2D Mesh, for which a solution was developed here.

Unfortunately, there is no way to save the updated Mesh in parallel, nor is it possible to create a SubMesh in parallel.

Is there a way to map vertex values from a SubMesh back to a Mesh directly without interpolation? This would bipass the interpolation step and allow conversion of the Function outside the parallel environment.

The SubMesh page does mention a "parent_vertex_indices,” but I do not see any such variable in my SubMesh instance.

Comments

Does it help to use something like submesh.set_parent(mesh)?

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that'll setup the parent mesh, but that does not provide access to any new mappings...

Answer 1

The parent_vertex_indices are stored in a MeshData object acquired from SubMesh.data().

Comments

running

d = submesh.data()

with the latest dolfin-stable and unstable, I'm not seeing this.

In IPython tab-complete:

In [10]: d
Out[10]: <dolfin.cpp.mesh.MeshData; proxy of <Swig Object of type 'boost::shared_ptr< dolfin::MeshData > *' at 0x37c6990> >

In [11]: d.
d.array                 d.exists                d.parameters
d.clear                 d.id                    d.rename
d.create_array          d.label                 d.str
d.create_mesh_function  d.mesh_function         d.this
d.erase_array           d.name                  d.thisown

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I believe the correct syntax to access this in the latest dolfin versions is:

submesh.data().array('parent_vertex_indices', 0)

Does this do what you want?

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LOL! yes, thank you.