[petsc-users] arkimex rejecting all dt in petsc 3.6.0
Italo Tasso
italo at tasso.com.br
Thu Jun 18 22:31:28 CDT 2015
I understand.
Thanks again.
On Thu, Jun 18, 2015 at 10:58 PM, Emil Constantinescu <emconsta at mcs.anl.gov>
wrote:
> The results enclosed for 3.5.4 (354.txt) are not correct. I can tell that
> by looking at the first step. Most implicit schemes in arkimex have the
> first stage explicit and therefore need to be "started" somehow when
> dealing with algebraic constraints. In this case, a different scheme is
> used to start the integration.
>
> Note that in 3.6 and 3.5.4_SEGV the first step uses scheme 1bee
> (scheme=0:'1bee') and then switches to '3'. This is the correct sequence
> otherwise inconsistent initial conditions are inadvertently used or the
> solver thinks it solves an ODE. I'm not sure why it's crashing in
> 3.5.4_SEGV. Configuring with --with-debugging=yes may reveal more.
>
> Emil
>
> On 6/18/15 4:10 PM, Italo Tasso wrote:
>
>> Thank you Barry and Emil.
>>
>> It works, but it takes twice as many steps than before.
>>
>> Was it wrong before? Should I have been using this option all along?
>>
>> I am solving the Navier-Stokes equations, full implicit and non-linear.
>>
>> I also noticed two things:
>>
>> In the 3.6.0 output, ts_monitor skips timestep #1.
>>
>> If I use the equation type in 3.5.4, I get segmentation fault.
>>
>> I attached the outputs.
>>
>>
>>
>>
>>
>> On Thu, Jun 18, 2015 at 1:24 PM, Emil Constantinescu
>> <emconsta at mcs.anl.gov <mailto:emconsta at mcs.anl.gov>> wrote:
>>
>> No, I'm not sure if it should. It belongs to the same category as
>> "problem_type" == TS_LINEAR / == TS_NONLINEAR.
>>
>> Emil
>>
>>
>> On 6/18/15 11:15 AM, Abhyankar, Shrirang G. wrote:
>>
>> Can the DAE equation type be supplied via a run-time option?
>>
>> Shri
>>
>> -----Original Message-----
>> From: barry smith <bsmith at mcs.anl.gov <mailto:bsmith at mcs.anl.gov
>> >>
>> Date: Thursday, June 18, 2015 at 11:08 AM
>> To: Italo Tasso <italo at tasso.com.br
>> <mailto:italo at tasso.com.br>>, "Constantinescu, Emil M."
>> <emconsta at mcs.anl.gov <mailto:emconsta at mcs.anl.gov>>
>> Cc: "petsc-users at mcs.anl.gov <mailto:petsc-users at mcs.anl.gov>"
>> <petsc-users at mcs.anl.gov <mailto:petsc-users at mcs.anl.gov>>
>> Subject: Re: [petsc-users] arkimex rejecting all dt in petsc 3.6.0
>>
>>
>> Here is the response from Emil who made the changes to
>> the code
>>
>> If you are solving a DAE then in the new version, we
>> introduced a new
>> flag that distinguishes between ODEs and DAEs leading to
>> different
>> semantics. For DAEs this is needed b/c it may not have
>> consistent initial
>> conditions.
>>
>> If solving DAEs, the user has to set the EquationType
>> appropriately:
>> e.g.,
>> ierr =
>> TSSetEquationType(ts,TS_EQ_DAE_IMPLICIT_INDEX1);CHKERRQ(ierr);
>>
>> This is documented in the doc, but I didn't add it to the
>> changelog (Jed
>> pointed it out to me).
>>
>> Currently it only affects -ts_type arkimex. I'll work with
>> Satish to add
>> it to the changelog.
>>
>> *If that's not the case:* let me know and we can dig deeper.
>>
>> Emil
>>
>> On Jun 18, 2015, at 5:48 AM, Italo Tasso
>> <italo at tasso.com.br <mailto:italo at tasso.com.br>> wrote:
>>
>> I just upgraded to 3.6.0 and my code stopped working.
>> All dt are
>> rejected. I used the same configure line, same code,
>> same everything.
>>
>> With 3.5.4 I get:
>>
>> 0 TS dt 1e-06 time 0
>> 0 SNES Function norm 2.549981005316e+05
>> 1 SNES Function norm 6.107056905987e-03
>> 2 SNES Function norm 1.483881932064e-10
>> 3 SNES Function norm 9.122873794272e-11
>> Nonlinear solve converged due to CONVERGED_FNORM_ABS
>> iterations 3
>> 0 SNES Function norm 7.790429171165e+04
>> 1 SNES Function norm 7.289068747803e-04
>> 2 SNES Function norm 8.227639633330e-11
>> Nonlinear solve converged due to CONVERGED_FNORM_ABS
>> iterations 2
>> 0 SNES Function norm 1.154356516184e+05
>> 1 SNES Function norm 2.309925413255e-03
>> 2 SNES Function norm 6.382141981406e-11
>> Nonlinear solve converged due to CONVERGED_FNORM_ABS
>> iterations 2
>> TSAdapt 'basic': step 0 accepted t=0
>> + 1.000e-06
>> wlte=0.000654 family='arkimex' scheme=0:'3' dt=1.000e-05
>>
>> With 3.6.0 I get:
>>
>> 0 TS dt 1e-06 time 0
>> 0 SNES Function norm 2.549981005316e+05
>> 1 SNES Function norm 6.107056925316e-03
>> 2 SNES Function norm 1.519319591792e-10
>> 3 SNES Function norm 9.070104116945e-11
>> Nonlinear solve converged due to CONVERGED_FNORM_ABS
>> iterations 3
>> 0 SNES Function norm 7.790429171165e+04
>> 1 SNES Function norm 6.942541792651e-04
>> 2 SNES Function norm 8.458781909516e-11
>> Nonlinear solve converged due to CONVERGED_FNORM_ABS
>> iterations 2
>> 0 SNES Function norm 1.154356516184e+05
>> 1 SNES Function norm 2.287202942961e-03
>> 2 SNES Function norm 6.585201377573e-11
>> Nonlinear solve converged due to CONVERGED_FNORM_ABS
>> iterations 2
>> TSAdapt 'basic': step 0 rejected t=0
>> + 1.000e-06 wlte=
>> 324 family='arkimex' scheme=0:'3' dt=1.311e-07
>>
>> Any ideas? I attached the full output.
>>
>> Options I use:
>>
>> -ts_view -ts_type arkimex -ts_arkimex_fully_implicit
>> -ts_adapt_monitor
>> -ts_monitor -snes_monitor -snes_converged_reason
>> -ksp_type preonly
>> -pc_type lu -pc_factor_mat_solver_package mumps
>> -snes_rtol 0 -snes_atol
>> 1e-10 -snes_stol 0
>>
>> <petsc354.txt><petsc360.txt>
>>
>>
>>
>>
>>
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