Hi,
I am trying to understand the dof numbering a bit better.
The simulation I have at hand is that of a solid mechanics problem with
thermal load. This has a total of ~770,000 dofs, and so far none of the
iterative solves in petsc has provided good convergence property. Hence, I am
stuck with using direct solvers.
As a result, it is important for me to have a fill reducing dof numbering
for my problems. Some of my dofs are coupled only through the dof constraints,
not through a physical element connectivity. I have two different sets of such
coupling constraints. One set is applied independently, and the second set is
applied in addition to the first set.
What I have observed is that the -ksp_type preonly -pc_type lu is able to
solve with only the first set of dof constraints applied (but takes a lot of
memory ~16 GB, which is all that my computer has). However, petsc complains
about insufficient memory when I apply the second set in addition to the first.
I suspect that renumbering the dofs using a fill-reducing criteria by
accounting for these dof constraints could address the problem. However, I am
not sure if the current code setup allows this to be done in libMesh. What I
see is that the partitioners are associated with the MeshBase class, without
any information from the DofMap.
I would appreciate any insight in this matter.
Thanks,
Manav
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