[Mesa-users] Convergence problem in ppisn/pisn models

[Ebraheem Farag]

Hello Debasish,

It's nice to hear you've solved your issue!

Just something to keep in mind if you plan to move forward with a reduced
varcontrol_target:

We have found that the ppisn inlists (using the latest c12ag rate) are
quite sensitive (in MESA) to temporal and mesh resolution near the black
hole mass spectrum peak.

If you plan to continue down this route of calculating ppisn models, I
suggest you check out Resolving The Peak of The Black Hole Mass Spectrum
<https://iopscience.iop.org/article/10.3847/1538-4357/ac8b83>.
In this paper, we conducted many numerical convergence tests of the farmer
et al. 2020 models (very similar to farmer et al. 2019, but in r11701).
We ran models with up to 30000 zones and 2 million timesteps to resolve the
behavior of these inlists.

If you want a working example in r11701, you could try out our inlists,
which are an updated form of the farmer et al. 2019 inlists: Check out the
zenodo here <https://doi.org/10.5281/zenodo.6930577>.
We have included all the inlists and associated files for running pipisn
models at the highest resolutions, with pgstar movies provided to help
visualize and debug.

a couple notes (if you plan to go down the ppisn rabbit hole):
-  z = 10^-5 was adopted in Resolving The Peak of The Black Hole Mass
Spectrum <https://iopscience.iop.org/article/10.3847/1538-4357/ac8b83>
- It's probably a good idea to make sure you are using a high resolution
c12(alpha,gamma)16O reaction rate. we adopted the most recent rate from (Deboer
et. al 2017
<https://journals.aps.org/rmp/abstract/10.1103/RevModPhys.89.035007>)
updated with >2000+ temperature points in Mehta et. al 2022
<https://iopscience.iop.org/article/10.3847/1538-4357/ac3130/meta>, as
opposed to the default rate shipped with mesa.
- We ran these models with varcontrol_target = 5d-5.
- adopting a minimum diffusive mixing coefficient can help achieve
numerical convergence sooner in low resolution ppisn models. (see the paper
and our inlists for details)

Best of luck!

-EbF

On Mon, Feb 13, 2023 at 9:45 AM Debasish Dutta via Mesa-users <
mesa-users at lists.mesastar.org> wrote:

> Hi, I turned off the varcontrol_target and it seemed to have worked.
> Earlier, the pulsations began but the code did not proceed till collapse. I
> am attaching a movie of my earlier run. Thanks Debasish ᐧ On Mon, 13 Feb
> 2023 at 22: 13, Debasish
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> Hi,
> I turned off the varcontrol_target and it seemed to have worked. Earlier,
> the pulsations began but the code did not proceed till collapse. I am
> attaching a movie of my earlier run.
>
> Thanks
> Debasish
> ᐧ
>
> On Mon, 13 Feb 2023 at 22:13, Debasish Dutta <debasishdutta1707 at gmail.com>
> wrote:
>
>> Hi,
>> I turned off the varcontrol_target and it seemed to have worked. Earlier,
>> the pulsations began but the code did not proceed till collapse. I am
>> attaching a movie of my earlier run.
>>
>> Thanks
>> Debasish
>> ᐧ
>>
>> On Mon, 13 Feb 2023 at 15:56, Rob Farmer <robert.j.farmer37 at gmail.com>
>> wrote:
>>
>>> Hi
>>>
>>> So what have you tried to fix this problem? Have you tried varying any
>>> other parameters? Have you made any plots to determine what the star is
>>> doing?
>>>
>>> Rob
>>>
>>>
>>> On Sun, 12 Feb 2023, 18:49 Debasish Dutta via Mesa-users, <
>>> mesa-users at lists.mesastar.org> wrote:
>>>
>>>> Hi,
>>>> I am trying to run some ppisn/pisn models and reproduce some results of Farmer
>>>> et. al (2019)
>>>> <https://urldefense.com/v3/__https://streaklinks.com/BZDi9rv6OsormvBOegYImcHx/https*3A*2F*2Fdoi.org*2F10.3847*2F1538-4357*2Fab518b__;JSUlJSUl!!KGKeukY!w7VbXpt_C55mpJ0i151Fye45_jWORDRT1dRNrDghVHqaA7jlTvDrJdm6gU8vms5zCYs5wp3Yza9dzadfRjAOtFSaVquEL_GOnAsEDA$>.
>>>> I ran some models of 35, 40, 45,........,100 solar masses (mellaticlity
>>>> 10-3). However, I am facing convergence problems in the 70 solar mass
>>>> model. I get this error message
>>>>
>>>> stopping because of convergence problems dt < min_timestep_limit
>>>> terminated evolution: convergence problems
>>>> termination code: min_timestep_limit
>>>>
>>>> I am using mesa version r11532.
>>>>
>>>> Thanks and regards
>>>>
>>>> Debasish Dutta
>>>>
>>>> ᐧ
>>>> _______________________________________________
>>>> mesa-users at lists.mesastar.org
>>>> https://lists.mesastar.org/mailman/listinfo/mesa-users
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>>>>
>>>> _______________________________________________
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