[petsc-users] puzzling arkimex logic

[Mark Adams]

Thanks, it is working fine.
Mark

On Wed, Jan 4, 2023 at 1:12 PM Jed Brown <jed at jedbrown.org> wrote:

> This default probably shouldn't be zero, and probably lengthening steps
> should be more gentle after a recent failure. But Mark, please let us know
> if what's there works for you.
>
> "Zhang, Hong via petsc-users" <petsc-users at mcs.anl.gov> writes:
>
> > Hi Mark,
> >
> > You might want to try -ts_adapt_time_step_increase_delay to delay
> increasing the time step after it has been decreased due to a failed solve.
> >
> > Hong (Mr.)
> >
> >> On Jan 2, 2023, at 12:17 PM, Mark Adams <mfadams at lbl.gov> wrote:
> >>
> >> I am using arkimex and the logic with a failed KSP solve is puzzling.
> This step starts with a dt of ~.005, the linear solver fails and cuts the
> time step by 1/4. So far, so good. The step then works but the next time
> step the time step goes to ~0.006.
> >> TS seems to have forgotten that it had to cut the time step back.
> >> Perhaps that logic is missing or my parameters need work?
> >>
> >> Thanks,
> >> Mark
> >>
> >> -ts_adapt_dt_max 0.01 # (source: command line)
> >> -ts_adapt_monitor # (source: file)
> >> -ts_arkimex_type 1bee # (source: file)
> >> -ts_dt .001 # (source: command line)
> >> -ts_max_reject 10 # (source: file)
> >> -ts_max_snes_failures -1 # (source: file)
> >> -ts_max_steps 8000 # (source: command line)
> >> -ts_max_time 14 # (source: command line)
> >> -ts_monitor # (source: file)
> >> -ts_rtol 1e-6 # (source: command line)
> >> -ts_type arkimex # (source: file)
> >>
> >>   Nonlinear solve converged due to CONVERGED_SNORM_RELATIVE iterations 2
> >>       TSAdapt basic arkimex 0:1bee step   1 accepted t=0.001      +
> 2.497e-03 dt=5.404e-03  wlte=0.173  wltea=   -1 wlter=
> >>  -1
> >> 2 TS dt 0.00540401 time 0.00349731
> >>     0 SNES Function norm 1.358886930084e-05
> >>     Linear solve did not converge due to DIVERGED_ITS iterations 100
> >>   Nonlinear solve did not converge due to DIVERGED_LINEAR_SOLVE
> iterations 0
> >>       TSAdapt basic step   2 stage rejected (DIVERGED_LINEAR_SOLVE)
> t=0.00349731 + 5.404e-03 retrying with dt=1.351e-03
> >>     0 SNES Function norm 1.358886930084e-05
> >>     Linear solve converged due to CONVERGED_RTOL iterations 19
> >>     1 SNES Function norm 4.412110425362e-10
> >>     Linear solve converged due to CONVERGED_RTOL iterations 6
> >>     2 SNES Function norm 4.978968053066e-13
> >>   Nonlinear solve converged due to CONVERGED_SNORM_RELATIVE iterations 2
> >>     0 SNES Function norm 8.549322067920e-06
> >>     Linear solve converged due to CONVERGED_RTOL iterations 14
> >>     1 SNES Function norm 8.357075378456e-11
> >>     Linear solve converged due to CONVERGED_RTOL iterations 4
> >>     2 SNES Function norm 4.983138402512e-13
> >>   Nonlinear solve converged due to CONVERGED_SNORM_RELATIVE iterations 2
> >>     0 SNES Function norm 1.044832467924e-05
> >>     Linear solve converged due to CONVERGED_RTOL iterations 13
> >>     1 SNES Function norm 1.036101875301e-10
> >>     Linear solve converged due to CONVERGED_RTOL iterations 4
> >>     2 SNES Function norm 4.984888077288e-13
> >>   Nonlinear solve converged due to CONVERGED_SNORM_RELATIVE iterations 2
> >>       TSAdapt basic arkimex 0:1bee step   2 accepted t=0.00349731 +
> 1.351e-03 dt=6.305e-03  wlte=0.0372  wltea=   -1 wlter=
> >>   -1
> >> 3 TS dt 0.00630456 time 0.00484832
> >>     0 SNES Function norm 8.116559104264e-06
> >>     Linear solve did not converge due to DIVERGED_ITS iterations 100
>
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