[petsc-users] pseudo-transient ?

[Jed Brown]

Please always use "reply-all" so that your messages go to the list.
This is standard mailing list etiquette.  It is important to preserve
threading for people who find this discussion later and so that we do
not waste our time re-answering the same questions that have already
been answered in private side-conversations.  You'll likely get an
answer faster that way too.


It doesn't affect the final result, just the algorithm to get there.
Read this doc update.

https://bitbucket.org/petsc/petsc/commits/b813ae3b0839847a3f9c27668d2815c374454af5

I have an email thread with the authors from 2010, but this was the
conclusion.  I don't have time to test reproducing the figures from the
paper and the above-mentioned linearly implicit variant (the algorithm
they intended to run), but if you're experimenting with it, we would
certainly welcome a patch to that effect.

Mohammad Hassan Baghaei <mhbaghaei at mail.sjtu.edu.cn> writes:

> Thank you very much for your help! I am currently reading the Coffey paper
> on the  pseudo-transient continuation method. Thanks for making clear for
> me. In fact, I need that the final converged solution will be in fully
> implicit form. So, I think I have to configure the SNES.
>
> -----Original Message-----
> From: Jed Brown [mailto:jed at jedbrown.org] 
> Sent: Wednesday, February 7, 2018 6:40 AM
> To: Smith, Barry F. <bsmith at mcs.anl.gov>; Mohammad Hassan Baghaei
> <mhbaghaei at mail.sjtu.edu.cn>
> Cc: petsc-users at mcs.anl.gov
> Subject: Re: [petsc-users] pseudo-transient ?
>
> src/ts/examples/tutorials/ex26.c solves the same problem as that (since
> removed) src/snes/examples/tutorials/ex27.c referenced in the Coffey paper.
>
> Unfortunately, there is still a dangling reference from the TS example that
> needs to be fixed.
>
> Note that there is a slight mistake in the paper -- they describe the
> algorithm as linearly implicit but the numerical results were created using
> nonlinearly implicit Euler.  The algorithm as described is more efficient
> and the default using TSPSEUDO in the TS example.  If you want to reproduce
> the numerical results, you'll have to change the SNES to converge the
> nonlinear solve instead of just the first step.
>
> "Smith, Barry F." <bsmith at mcs.anl.gov> writes:
>
>>   That example has not likely existed for many year. You can use
> src/ts/examples/tutorials/ex1.c as a starting point.
>>
>>
>>
>>> On Feb 6, 2018, at 3:31 PM, Mohammad Hassan Baghaei
> <mhbaghaei at mail.sjtu.edu.cn> wrote:
>>> 
>>> Hi
>>> I wanted to use my solve the system of equation using pseudo-transient
> continuation. I found that we can refer to this version for driven cavity
> example. However, I could not find it within files
> (src/snes/examples/tutorials/ex27.c). Would it be possible for you to share
> this file? 
>>> Thanks
>>> Amir