PETSc Options for FSP in MOOSE

[TLWise]

Can the FSP App in MOOSE be used to implement the following?:
Given two variables, u and p.

For p, Geometric-Algebraic Multi-grid with Gauss-Siedel smoother.

For u, Preconditioned bi-conjugate gradient solver with diagonal based incomplete LU preconditioner.

Separately, can MOOSE use geometric multigrid solvers, SSOR/SOR and UMFPACK/SOR as solver/smoother pairs for variables u and p, respectively?

[GiudGiud]

hello

FSP is a MOOSE preconditioner. Is that the one you mean?
https://mooseframework.inl.gov/source/preconditioners/FieldSplitPreconditioner.html

For p, Geometric-Algebraic Multi-grid with Gauss-Siedel smoother.

Geometric multi-grid is not implemented. AMG is by selecting the relevant PETSc preconditionner
@lindsayad want to comment?

[TLWise]

Yes. You are spot on. This is the app I am attempting to apply to my problem.

"AMG is by selecting the relevant PETSc"

Can this be coded in total in MOOSE? If so are there any examples posted of its implementation?

[lindsayad]

Can this be coded in total in MOOSE?

What do you mean by this? No coding required for algebraic multigrid. The most commonly used algebraic multigrid preconditioner in MOOSE is -pc_type hypre -pc_hypre_type boomeramg. If you are talking about geometric multigrid, we have that capability in libMesh and we have plans to implement it in MOOSE within the next five years