Keep dof order in submeshes

Question

I edited the question, as it occured to me that keeping the original dof numbering might be impossible

Hello

I'd like to decompose a (global) mesh into several submeshes (e.g. by subdividing the global mesh into n times m submeshes, which are non-overlapping, but share dofs at common boundaries).

It would save me a lot of hassle if I could keep the dof ordering of the original mesh for the submeshes - so that the submesh dof are numbered {0, ..., #submeshdof}, but in the same order as the global mesh, e.g. a global mesh

9 7 1
6 2 3
4 8 5

which is decomposed into 2x2 subdomains has upper right subdomain dofs

4 1
2 3

and upper left subdomain dofs

4 3
2 1

Is this even possible? I'd like to emphasize that I not only want to keep the mesh vertex order, but rather the functionspace dof order.

I've read this thread, but I don't understand how to apply this for a meshfunction (python user here). Examples welcome!

Thanks!

Comments

Some time ago, I had the same problem as you. I did not find a solution to it, in the end i did it all with fenics functions instead of doing it on a DOF level. I would heavily restrain from manipulating the DOFs, and instead rely on the fenics functions.