[petsc-users] Solution "jumps" after setting timestep
Moritz.Huck at isea.rwth-aachen.de
Moritz.Huck at isea.rwth-aachen.de
Fri Dec 14 05:05:46 CST 2018
In this example yes.
-----Ursprüngliche Nachricht-----
Von: Emil Constantinescu <emconsta at mcs.anl.gov>
Gesendet: Donnerstag, 13. Dezember 2018 20:21
An: Zhang, Hong <hongzhang at anl.gov>; Huck, Moritz <Moritz.Huck at isea.rwth-aachen.de>
Cc: petsc-users <petsc-users at mcs.anl.gov>
Betreff: Re: [petsc-users] Solution "jumps" after setting timestep
Okay, so you start your integration with "TSSetMaxTime and then call TSSolve (TSSetExactFinalTime is set to TS_EXACTFINALTIME_MATCHSTEP)"
Then after it's done at t=2 you tell TS that TSSetTimeStep(ts,1e-3) and call TSSolve again?
Emil
On 12/13/18 11:36 AM, Zhang, Hong via petsc-users wrote:
> Please make sure your messages go to petsc-users when replying.
>
>> On Dec 13, 2018, at 11:25 AM, Moritz.Huck at isea.rwth-aachen.de
>> <mailto:Moritz.Huck at isea.rwth-aachen.de> wrote:
>>
>> The first solve to 1e-3
>> TSAdapt basic arkimex 0:1bee step 0 rejected t=0 +
>> 1.000e-03 dt=1.000e-04 wlte= 102 wltea= -1 wlter= -1
>> TSAdapt basic arkimex 0:1bee step 0 rejected t=0 +
>> 1.000e-04 dt=1.000e-05 wlte= 127 wltea= -1 wlter= -1
>> TSAdapt basic arkimex 0:1bee step 0 rejected t=0 +
>> 1.000e-05 dt=1.995e-06 wlte= 5.09 wltea= -1 wlter= -1
>> TSAdapt basic arkimex 0:1bee step 0 accepted t=0 +
>> 1.995e-06 dt=3.232e-06 wlte=0.309 wltea= -1 wlter= -1
>> TSAdapt basic arkimex 0:4 step 1 accepted t=1.99488e-06+
>> 3.232e-06 dt=3.232e-05 wlte=1.65e-06 wltea= -1 wlter= -1
>> TSAdapt basic arkimex 0:4 step 2 accepted t=5.22663e-06+
>> 3.232e-05 dt=3.232e-04 wlte=3.96e-05 wltea= -1 wlter= -1
>> TSAdapt basic arkimex 0:4 step 3 accepted t=3.75441e-05+
>> 3.232e-04 dt=6.393e-04 wlte=0.000973 wltea= -1 wlter= -1
>> TSAdapt basic arkimex 0:4 step 4 accepted t=0.000360719+
>> 6.393e-04 dt=2.962e-03 wlte=0.00142 wltea= -1 wlter= -1 the
>> solve steps afterwards:
>> TSAdapt basic arkimex 0:4 step 5 accepted t=0.001 +
>> 2.962e-03 dt=7.110e-03 wlte=0.0197 wltea= -1 wlter= -1
>> TSAdapt basic arkimex 0:4 step 6 accepted t=0.00396151 +
>> 7.110e-03 dt=2.489e-02 wlte=0.00437 wltea= -1 wlter= -1
>> TSAdapt basic arkimex 0:4 step 7 accepted t=0.0110717 +
>> 2.489e-02 dt=7.079e-02 wlte= 0.01 wltea= -1 wlter= -1
>> TSAdapt basic arkimex 0:4 step 8 accepted t=0.03596 +
>> 7.079e-02 dt=9.672e-02 wlte=0.188 wltea= -1 wlter= -1
>> TSAdapt basic arkimex 0:4 step 9 accepted t=0.106753 +
>> 9.672e-02 dt=1.329e-01 wlte=0.184 wltea= -1 wlter= -1 around
>> here it reaches a steady state
>> TSAdapt basic arkimex 0:4 step 10 accepted t=0.203478 +
>> 1.329e-01 dt=2.432e-01 wlte=0.0586 wltea= -1 wlter= -1
>> TSAdapt basic arkimex 0:4 step 11 accepted t=0.336424 +
>> 2.432e-01 dt=4.536e-01 wlte=0.0542 wltea= -1 wlter= -1
>> TSAdapt basic arkimex 0:4 step 12 accepted t=0.579616 +
>> 4.536e-01 dt=1.112e+00 wlte=0.0182 wltea= -1 wlter= -1
>> TSAdapt basic arkimex 0:4 step 13 accepted t=1.03324 +
>> 9.668e-01 dt=3.286e+00 wlte=0.00492 wltea= -1 wlter= -1 here I
>> set the timestep to 1e-3 artificially and the solution deviates from
>> the steady state solution
>
> The TS time jumps between step 13 and step 14, which is probably the
> cause of the jump in the solution.
> Did you reset the time to t=2 by calling TSSetTime() after step 13?
>
> Hong
>
>> TSAdapt basic arkimex 0:4 step 14 accepted t=2 +
>> 1.000e-03 dt=3.845e-03 wlte=0.003 wltea= -1 wlter= -1
>> TSAdapt basic arkimex 0:4 step 15 accepted t=2.001 +
>> 3.845e-03 dt=3.845e-02 wlte=6.95e-06 wltea= -1 wlter= -1
>> TSAdapt basic arkimex 0:4 step 16 accepted t=2.00485 +
>> 3.845e-02 dt=3.845e-01 wlte=4.31e-05 wltea= -1 wlter= -1
>> TSAdapt basic arkimex 0:4 step 17 accepted t=2.0433 +
>> 3.845e-01 dt=2.473e+00 wlte=0.000384 wltea= -1 wlter= -1
>> TSAdapt basic arkimex 0:4 step 18 accepted t=2.42784 +
>> 2.473e+00 dt=4.540e+00 wlte=0.0578 wltea= -1 wlter= -1 this
>> point is "back on track"
>> TSAdapt basic arkimex 0:4 step 19 accepted t=4.90058 +
>> 4.540e+00 dt=4.649e+00 wlte=0.596 wltea= -1 wlter= -1
>> *Von:*Zhang, Hong <hongzhang at anl.gov <mailto:hongzhang at anl.gov>>
>> *Gesendet:*Donnerstag, 13. Dezember 2018 17:39 *An:*Huck, Moritz
>> <Moritz.Huck at isea.rwth-aachen.de
>> <mailto:Moritz.Huck at isea.rwth-aachen.de>>
>> *Cc:*petsc-users at mcs.anl.gov <mailto:petsc-users at mcs.anl.gov>
>> *Betreff:*Re: [petsc-users] Solution "jumps" after setting timestep
>> Can you show the outputs of -ts_monitor for both cases (one with
>> oscillations and one without)?
>> Thanks,
>> Hong
>>
>>
>> On Dec 13, 2018, at 9:48 AM,Moritz.Huck at isea.rwth-aachen.de
>> <mailto:Moritz.Huck at isea.rwth-aachen.de>wrote:
>> Hi,
>> Sure after reaching a steady state it looks like this:
>> 0 SNES Function norm 3.767377637168e-03
>> 1 SNES Function norm 2.529971638368e-05
>> 2 SNES Function norm 4.433873358247e-09
>> 3 SNES Function norm 4.535675922104e-11
>> 0 SNES Function norm 9.898938706929e-04
>> 1 SNES Function norm 1.322473621975e-05
>> 2 SNES Function norm 1.672724799379e-09
>> 3 SNES Function norm 1.338501638801e-11
>> 0 SNES Function norm 1.624500221071e-03
>> 1 SNES Function norm 2.448515345247e-05
>> 2 SNES Function norm 6.225549426481e-09
>> 3 SNES Function norm 1.062516222150e-10
>> 4 SNES Function norm 6.493758120241e-13
>> 0 SNES Function norm 1.106311709708e-03
>> 1 SNES Function norm 2.475673243430e-05
>> 2 SNES Function norm 9.969586735411e-09
>> 3 SNES Function norm 2.479591395229e-10
>> 4 SNES Function norm 1.542689576708e-12
>> 0 SNES Function norm 6.070943996748e-04
>> 1 SNES Function norm 1.648134285171e-05
>> 2 SNES Function norm 8.461078655420e-09
>> 3 SNES Function norm 2.480863447790e-10
>> 4 SNES Function norm 1.513977618851e-12
>> TSAdapt basic arkimex 0:4 step 15 accepted t=5.67201 +
>> 4.328e+00 dt=4.687e+00 wlte$
>> 0.477 wltea= -1 wlter= -1
>> If I set the next target time (in tssolve) to be tlast+1e-3 it
>> looks like this:
>> 0 SNES Function norm 4.734802409365e-03
>> 1 SNES Function norm 6.173939866359e-13
>> 0 SNES Function norm 5.633294284900e-04
>> 1 SNES Function norm 3.575533754564e-13
>> 0 SNES Function norm 9.651618110271e-04
>> 1 SNES Function norm 6.863177319359e-13
>> 0 SNES Function norm 7.706102281617e-04
>> 1 SNES Function norm 8.490865565002e-13
>> 0 SNES Function norm 5.028108294534e-04
>> 1 SNES Function norm 6.905750968862e-13
>> TSAdapt basic arkimex 0:4 step 16 accepted t=10 +
>> 1.000e-03 dt=2.612e-03 wlte$
>> 0.0141 wltea= -1 wlter= -1
>> The SNES solver has a atoll of 1e-10, setting the atoll to lower
>> values does not change the result.
>> Thank you,
>> Moritz
>> *Von:*Zhang, Hong <hongzhang at anl.gov <mailto:hongzhang at anl.gov>>
>> *Gesendet:*Donnerstag, 13. Dezember 2018 16:42
>> *An:*Huck, Moritz <Moritz.Huck at isea.rwth-aachen.de
>> <mailto:Moritz.Huck at isea.rwth-aachen.de>>
>> *Cc:*petsc-users at mcs.anl.gov <mailto:petsc-users at mcs.anl.gov>
>> *Betreff:*Re: [petsc-users] Solution "jumps" after setting timestep
>> Can you please add command line options -ts_monitor -snes_monitor
>> and show us the outputs?
>> Thanks,
>> Hong (Mr.)
>>
>>
>>
>> On Nov 4, 2018, at 6:19 AM, Moritz.Huck--- via petsc-users
>> <petsc-users at mcs.anl.gov <mailto:petsc-users at mcs.anl.gov>> wrote:
>> Hi,
>>
>> I using the basic adaptor.
>> If I let the adaptor handle everything it does not oscillates.
>> I don’t mean setting the timestep at the start (which does not
>> produces the
>> problem),
>> I need to set during runtime between two steps.
>>
>> Best Regards,
>>
>> Moritz
>>
>> -----Ursprüngliche Nachricht-----
>> Von: Constantinescu, Emil M. <emconsta at anl.gov
>> <mailto:emconsta at anl.gov>>
>> Gesendet: Samstag, 3. November 2018 15:43
>> An: Huck, Moritz <Moritz.Huck at isea.rwth-aachen.de
>> <mailto:Moritz.Huck at isea.rwth-aachen.de>>;petsc-users at mcs.anl.gov
>> <mailto:petsc-users at mcs.anl.gov>
>> Betreff: Re: [petsc-users] Solution "jumps" after setting
>> timestep
>>
>> On 11/3/18 4:56 AM, Moritz.Huck--- via petsc-users wrote:
>>
>>
>> Hi,
>>
>> I am using the IMEX Runge Kutta to solve an implicit DAE
>> (G=0).
>>
>> When I manually set the time step (TSSetTimestep) my
>> solution jumps.
>>
>>
>> When you don't set the time step, does it still oscillates? If
>> not, can you
>> check if it oscillates when reducing the fixed initial time step?
>> Did you turn the adaptivity off (-ts_adapt_type none)?
>>
>> Emil
>>
>>
>>
>>
>> If I go from a steady state to the same state, it
>> oscillates a few
>> time and comes back to the steady solution.
>>
>> Can this be prevented?
>>
>> Thank you,
>>
>> Moritz
>>
>
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