[petsc-users] Using nonzero -pc_hypre_boomeramg_restriction_type in field split

[Alexander Lindsay]

Good to know. I may take a shot at it depending on need and time! Opened
https://gitlab.com/petsc/petsc/-/issues/1362 for doing so

Alex

On Sun, Apr 16, 2023 at 9:27 PM Pierre Jolivet <pierre.jolivet at lip6.fr>
wrote:

>
> On 17 Apr 2023, at 1:10 AM, Alexander Lindsay <alexlindsay239 at gmail.com>
> wrote:
>
> Are there any plans to get the missing hook into PETSc for AIR? Just
> curious if there’s an issue I can subscribe to or anything.
>
>
> Not that I know of, but it would make for a nice contribution if you feel
> like creating a PR.
>
> Thanks,
> Pierre
>
> (Independently I’m excited to test HPDDM out tomorrow)
>
> On Apr 13, 2023, at 10:29 PM, Pierre Jolivet <pierre.jolivet at lip6.fr>
> wrote:
>
> 
>
> On 14 Apr 2023, at 7:02 AM, Alexander Lindsay <alexlindsay239 at gmail.com>
> wrote:
>
> Pierre,
>
> This is very helpful information. Thank you. Yes I would appreciate those
> command line options if you’re willing to share!
>
>
> No problem, I’ll get in touch with you in private first, because it may
> require some extra work (need a couple of extra options in PETSc
> ./configure), and this is not very related to the problem at hand, so best
> not to spam the mailing list.
>
> Thanks,
> Pierre
>
> On Apr 13, 2023, at 9:54 PM, Pierre Jolivet <pierre.jolivet at lip6.fr>
> wrote:
>
> 
>
> On 13 Apr 2023, at 10:33 PM, Alexander Lindsay <alexlindsay239 at gmail.com>
> wrote:
>
> Hi, I'm trying to solve steady Navier-Stokes for different Reynolds
> numbers. My options table
>
> -dm_moose_fieldsplit_names u,p
> -dm_moose_nfieldsplits 2
> -fieldsplit_p_dm_moose_vars pressure
> -fieldsplit_p_ksp_type preonly
> -fieldsplit_p_pc_type jacobi
> -fieldsplit_u_dm_moose_vars vel_x,vel_y
> -fieldsplit_u_ksp_type preonly
> -fieldsplit_u_pc_hypre_type boomeramg
> -fieldsplit_u_pc_type hypre
> -pc_fieldsplit_schur_fact_type full
> -pc_fieldsplit_schur_precondition selfp
> -pc_fieldsplit_type schur
> -pc_type fieldsplit
>
> works wonderfully for a low Reynolds number of 2.2. The solver performance
> crushes LU as I scale up the problem. However, not surprisingly this
> options table struggles when I bump the Reynolds number to 220. I've read
> that use of AIR (approximate ideal restriction) can improve performance for
> advection dominated problems. I've tried
> setting -pc_hypre_boomeramg_restriction_type 1 for a simple diffusion
> problem and the option works fine. However, when applying it to my
> field-split preconditioned Navier-Stokes system, I get immediate
> non-convergence:
>
>  0 Nonlinear |R| = 1.033077e+03
>       0 Linear |R| = 1.033077e+03
>   Linear solve did not converge due to DIVERGED_NANORINF iterations 0
> Nonlinear solve did not converge due to DIVERGED_LINEAR_SOLVE iterations 0
>
> Does anyone have an idea as to why this might be happening?
>
>
> Do not use this option, even when not part of PCFIELDSPLIT.
> There is some missing plumbing in PETSc which makes it unusable, see Ben’s
> comment here
> https://github.com/hypre-space/hypre/issues/764#issuecomment-1353452417.
> In fact, it’s quite easy to make HYPRE generate NaN with a very simple
> stabilized convection—diffusion problem near the pure convection limit
> (something that ℓAIR is supposed to handle).
> Even worse, you can make HYPRE fill your terminal with printf-style
> debugging messages
> https://github.com/hypre-space/hypre/blob/5546cc22d46b3dba253849f258786da47c9a7b21/src/parcsr_ls/par_lr_restr.c#L1416 with
> this option turned on.
> As a result, I have been unable to reproduce any of the ℓAIR results.
> This also explains why I have been using plain BoomerAMG instead of ℓAIR
> for the comparison in page 9 of https://arxiv.org/pdf/2201.02250.pdf (if
> you would like to try the PC we are using, I could send you the command
> line options).
>
> Thanks,
> Pierre
>
> If not, I'd take a suggestion on where to set a breakpoint to start my own
> investigation. Alternatively, I welcome other preconditioning suggestions
> for an advection dominated problem.
>
> Alex
>
>
>
>
>
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