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@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 <mfad...@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