[petsc-users] Preconditioned JFNK using SuperLU_dist for time dependent problems

[Hong Zhang]

Travis :

"SAME_NONZERO_PATTERN" should be used in your case.
It is likely a bug that causes  the segmentation violation.

Which packages do you use, superlu (sequential) or superlu_dist (parallel)?
superlu_dist does not support ilu.

Are you using latest petsc-dev? We fixed  bugs in petsc-dev and reset default
superlu_dist options. Please try
1) use petsc-dev
2) turn off superlu_dist options with runtime options
'-mat_superlu_dist_equil NO -mat_superlu_dist_rowperm NATURAL
-mat_superlu_dist_colperm NATURAL '
3) try parallel direct solver mumps

Let us know what you get.

Hong

> I ran into the following problem when trying to use superlu_dist as a
> preconditioner for matrix free SNES with GMRES in my high order Navier
> Stokes solver:
>
> I set the nonzero pattern of my preconditioner matrix at the begging of a
> simulation (t=0). The overall stencil of the numerical method never changes,
> so the nonzero pattern should never change. I use an implicit Runge Kutta
> scheme to advance the solution in time. The preconditioning matrix is the
> frozen jacobian at the start of a time step. The same preconditioner is used
> for every stage of the RK scheme. After one time step is complete, the
> preconditioner matrix is calculated for the new time step.
>
> The problem I am having with superlu_dist is that if I use
> SAME_NONZERO_PATTERN, I get a segmentation violation. However, if I use
> DIFFERENT_NONZERO_PATTERN, everything works fine. If I am conservative about
> how I initialize the nonzero pattern and desire it to never to change, why
> do I need to use DIFFERENT_NONZERO_PATTERN? Individual components in the
> nonzero structure will be zero for some steps and not others, but the
> overall nonzero structure is fixed. I don't get errors when using Additive
> Schwarz with ILU, but I am wondering if convergence problems occur because
> of how the nonzero patterns are handled. Any ideas of what I am doing
> incorrectly? What is SAME_NONZERO_PATTERN really telling the nonlinear
> solver over multiple calls? Most of the examples only have one call to
> SNESSolve, so I feel that this is not well covered elsewhere.
>
> Thanks in advance.
>
> Travis Fisher
>
>