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SubMesh of two subdomains

+7 votes

When extracting a submesh of a Dolfin mesh, I usually do something like
submesh = SubMesh(mesh, subdomains, 24)
Is it possible to extract the subdomain that is constituted by two or more subdomains, i.e.,
submesh = SubMesh(mesh, subdomains, [24, 25])
?

asked Jul 11, 2013 by nschloe FEniCS User (7,120 points)

1 Answer

+3 votes
 
Best answer

No you need to combine the two subdomains into one:

combined_subdomains = CellFunction("size_t", mesh, 0)
combined_subdomains.array()[subdomains.array()==24] = 1
combined_subdomains.array()[subdomains.array()==25] = 1
submesh = SubMesh(mesh, combined_subdomains, 1)

But it looks like a neat feature! Maybe you should consider implementing it and submit a pull request?

answered Jul 12, 2013 by johanhake FEniCS Expert (22,480 points)
selected Jul 12, 2013 by nschloe

Yes, that would be a nice feature.

commented Jul 12, 2013 by Garth N. Wells FEniCS Expert (35,930 points)

I filed a feature request for this at https://bitbucket.org/fenics-project/dolfin/issue/87/submesh-of-multiple-subdomains so we don't lose track.

commented Jul 12, 2013 by nschloe FEniCS User (7,120 points)

Analogical feature would be useful also for DirichletBC.

commented Jul 12, 2013 by Jan Blechta FEniCS Expert (51,420 points)
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