[FLASH-USERS] [EXTERNAL] Re: Use of implicit diffusion solver with AMR

[Adam Reyes]

Hi Madhav,

That specific error that you shared is more of a warning and just means
that the code won't be able to report reliable timing information for the
"PFFT_Init". If possible could you share a logfile from the run that blows
up? This would provide more information about how your problem is setup and
if anything could be recommended.

Admittedly I don't have much experience with the multigrid solvers, but
maybe someone who does could be of more help. Is there a reason that you're
using the split solver? The unsplit solver with HYPRE is a bit more used
for diffusion.

*************************************************************************
Adam Reyes

Code Group Leader, Flash Center for Computational Science
Research Scientist, Dept. of Physics and Astronomy
University of Rochester
River Campus: Bausch and Lomb Hall, 369
500 Wilson Blvd. PO Box 270171, Rochester, NY 14627
Email adam.reyes at rochester.edu
Web https://flash.rochester.edu
 (he / him / his)

*************************************************************************

On Tue, Apr 25, 2023 at 5:36 PM Madhav Nagori <mnagori at uncc.edu> wrote:

> Thank you very much for your reply. I have been trying to use the implicit
> diffusion with AMR, but I am not able to run it. I am getting the following
> error and then my solution diverges and blows up.
>
> *perfmon: ran out of space for timer, "PFFT_Init", cannot time this timer
> with perfmon*
>
> What I did was that I added the multigrid solver (REQUESTS
> Grid/GridSolvers/Multigrid/PfftTopLevelSolve/) to my Config file and added
> the corresponding runtime parameters in my *.par file* according to the
> FLASH manual. Is there anything else that needs to be added ? Kindly let me
> know.
>
> P.S: I am using the split solver which means that the time advancement
> code is solved by Thomas Algorithm. Would this have any connection with
> this error?
>
> Thank you for your time.
>
> On Wed, Apr 5, 2023 at 7:09 PM Hansen, Eddie <ehansen at pas.rochester.edu>
> wrote:
>
>> The user guide is referring to implicit magnetic diffusion. That one is
>> not yet supported for AMR. Currently, the implicit diffusion solvers with
>> AMR are for thermal conduction and radiation only.
>>
>> ******************************************
>> Eddie Hansen | Research Scientist
>> Flash Center for Computational Science
>> Dept. of Physics and Astronomy
>> University of Rochester, Rochester, NY
>> Cell 607-341-6126 | flash.rochester.edu
>> (he / him / his)
>> ******************************************
>> ------------------------------
>> *From:* flash-users <flash-users-bounces at flash.rochester.edu> on behalf
>> of Madhav Nagori <mnagori at uncc.edu>
>> *Sent:* Wednesday, April 5, 2023 10:31:48 AM
>> *To:* flash-users at flash.rochester.edu <flash-users at flash.rochester.edu>
>> *Subject:* [FLASH-USERS] Use of implicit diffusion solver with AMR
>>
>> Hello FLASH users and Development Team,
>>
>> I want to use the implicit diffusion solver for some very high resolution
>> cases of cell size 512*512*2048. For such high resolution, I want to use
>> AMR as the uniform mesh will take months to run.
>>
>> The user guide tells that the paramesh is not available to the implicit
>> diffusion solver. Is it possible to modify the code so that I can run with
>> AMR?
>>
>> P.S: I am using mass diffusion, viscosity diffusion and thermal diffusion
>> in my simulation. I tried using the explicit diffusion solver (Flux Based
>> Diffusion) with AMR, but that gave wrong results. However, the implicit
>> solver is providing the correct results.
>>
>> Please let me know.
>>
>> Thank You
>>
>> --
>> Best Regards,
>>
>> Madhav Nagori
>>
>> PhD Candidate | Laboratory for Multiscale Computational Fluid Dynamics
>> Department of Mechanical Engineering and Engineering Sciences
>> University of North Carolina at Charlotte
>> Office: Duke 273, 9330 Robert D. Snyder Rd, Charlotte, NC 28262, USA
>> Email: mnagori at uncc.edu
>> LinkedIn: www.linkedin.com/in/madhav-nagori
>>
>
>
> --
> Best Regards,
>
> Madhav Nagori
>
> PhD Candidate | Laboratory for Multiscale Computational Fluid Dynamics
> Department of Mechanical Engineering and Engineering Sciences
> University of North Carolina at Charlotte
> Office: Duke 273, 9330 Robert D. Snyder Rd, Charlotte, NC 28262, USA
> Email: mnagori at uncc.edu
> LinkedIn: www.linkedin.com/in/madhav-nagori
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