[Mesa-users] [EXT] PPISN Model Stalling in MESA-r24.03.1

[Mathieu Renzo]

Hi Trang,

 From your terminal output it looks like you're restarting from photo 
x950 and at model 20979 (19 steps later) the issue starts appearing. Are 
you changing anything in the inlist at this restart?
Have you tried restarting from a bit earlier? Have you tried slightly 
different masses? Do you have any models that worked to compare this 
crashing model to? (Maybe another mass in your grid?)

 From the masses, I suspect this is at the first pulse? If so, one thing 
to try is to change a bit the thresholds at which you switch from 
hydrostatic equilibrium to the HLLC solver (beware that you don't want 
to do that too early and "freeze" your simulation, nor too late and miss 
the beginning of the dynamical phase). This can be done with x_ctrl(1) 
in the test case setup, for example.

As a last resort, you may need to figure out exactly what residual is 
exceeding the tolerances: as you found, just making the tolerances 
larger, although it can sometimes help bypass small issues, it doesn't 
really solve the issues. Maybethis exercise from this year MESA Summer 
school 
<https://mesa-leuven.4d-star.org/tutorials/thursday/morning-session/>can 
be of guidance: it's not on PPISN, but retries because of max residuals 
are common in massive star evolution. The tasks of that exercise down to 
Task 5 should guide you to find what is the most problematic residual. 
Then, how to address that is something the MESA summer school exercise 
will not necessarily help with, but you will know more about why your 
model crash and hopefully that helps solving the issue.

Bests,
Mathieu

On 9/18/25 06:35, Trang Huynh via Mesa-users wrote:
> *
>
> *External Email*
>
> *
> ------------------------------------------------------------------------
>
> Dear all,
>
> I am currently simulating a pulsational pair-instability supernova 
> (PPISN) model using MESA-r24.03.1 and mesasdk version 24.7.1. The 
> setup is a non-rotating, 100 M⊙with  Z = 0 . My inlist and 
> run_star_extras.f90 files are based on the *ppisn* test-suite included 
> with this MESA release.
>
> The problem is my model struggles to enter the pair-instability regime 
> and consistently stalls during O-burning phase. I attempted increasing 
> |gold_tol_max_residual3| (from 1d-3 → 5d-3 → 5d-2), but the issue 
> persists. Below is a snippet from the terminal output of the last retries:
>
> Setting energy conservation error to zero until hydro is turned on for 
> the first time
>
> check gamma integral 3.6349043014391437E-002
>
> max_residual > tol_max_residual 26835 5.1008342853913410D-03 
> 5.0000000000000001D-03
>
> solver rejected trial model
>
> s% model_number 26835
>
> s% solver_call_number 33067
>
> nz 2861
>
> s% num_retries 6530
>
> dt 4.1498956078510518D-01
>
> log dt/secyer -7.8810667950730071D+00
>
> retry: max resid -- give up in solver 26835
>
> residual_norm > tol_residual_norm 26835 1.0776741982634678D-06 
> 9.9999999999999995D-07
>
> I would greatly appreciate any suggestions or best practices to help 
> the model progress into the pair-instability phase. To facilitate 
> feedback, I’ve attached the zip files with relevant |inlist| files, 
> |run_star_extras.f90|, full terminal output, and mesa build.log.
>
> Thank you in advance for your time and help!
>
> Best,
>
> *Trang N. Huynh *(she/her)
>
> PhD Student
>
> Department of Physics and Astronomy
>
> Louisiana State University
>
> thuyn27 at lsu.edu <mailto:thuyn27 at lsu.edu>
>
>
> _______________________________________________
> mesa-users at lists.mesastar.org
> https://lists.mesastar.org/mailman/listinfo/mesa-users
>
-- 
Mathieu Renzo <https://www.as.arizona.edu/~mrenzo/>
Assistant Professor
University of Arizona - Steward Observatory
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