[petsc-users] [petsc-maint] Preconditioners for KSPSolveTranspose() in linear elasticity

Jed Brown jed at jedbrown.org
Wed Jan 20 18:36:09 CST 2016

"Salazar De Troya, Miguel" <salazardetro1 at llnl.gov> writes:

> I am not 100% confident because I am not sure how libMesh handles the
> Dirichlet boundary conditions, 

How are you using libmesh?  Normally you write the boundary conditions.
Many of the examples use penalty conditions, which maintain symmetric
but have other problems.

> I am trying to speed up a two dimensional linear elasticity problem with isotropic and heterogeneous properties. It is a topology optimization problem, therefore some regions have an almost zero stiffness whereas other regions have a higher value, making the matrix ill-conditioned. So far, from having searched mail lists on similar problems, I have come up with the following CL options to pass to the petsc solver (two dimensional problem):
> -ksp_type cg -pc_type fieldsplit -pc_fieldsplit_block_size 2 -fieldsplit_pc_type hypre -fieldsplit_pc_hypre_type boomeramg -fieldsplit_pc_hypre_boomeramg_strong_threshold 0.7 -pc_fieldsplit_0 0,1

This option looks funny.  What are you trying to do here?

> -pc_fieldsplit_type symmetric_multiplicative -ksp_atol 1e-10
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