[Mesa-users] Convergence problems using other_D_mix with mesa-r15140

[Arman Aryaeipour]

Hi Frank,

Thank you for your suggestion, my apologies for the very delayed response. Your suggestion to set use_gold2_tolerences = .false. was helpful in allowing the model to go a little further forward in time during the mixing phase, but the model still runs into convergence issues and the timestep goes to zero before the implemented mixing phase can finish.

Best,
Arman

________________________________
From: Francis Timmes <fxt44 at mac.com>
Sent: 24 March 2021 23:43
To: Aryaeipour, Arman (PG/R - Physics) <a.aryaeipour at surrey.ac.uk>
Cc: Frank Timmes <fxt44 at mac.com>; mesa-users <mesa-users at lists.mesastar.org>
Subject: Re: [Mesa-users] Convergence problems using other_D_mix with mesa-r15140

as an experiment, try setting

     use_gold2_tolerances = .false.

fxt



> On Mar 24, 2021, at 12:51 PM, Arman Aryaeipour via Mesa-users <mesa-users at lists.mesastar.org> wrote:
>
> Hi Rob,
>
> Thank you for your quick response! I started by first loading in a 1 Msun white dwarf (regenerated with mesa-r15140) and accreting solar material atop it until the maximum temperature reached 10^8 K. At this point the run was stopped and saved as a model. I then started another run with this saved model and started the mixing.
>
> So, the terminal_output.txt file I've attached is MESAs output from the beginning of the mixing. Before that the accretion phase was also run with mesa-r15140 too.
>
> Many thanks,
> Arman
> From: Rob Farmer <r.j.farmer at uva.nl>
> Sent: 24 March 2021 19:34
> To: Aryaeipour, Arman (PG/R - Physics) <a.aryaeipour at surrey.ac.uk>
> Cc: mesa-users at lists.mesastar.org <mesa-users at lists.mesastar.org>
> Subject: Re: [Mesa-users] Convergence problems using other_D_mix with mesa-r15140
>
> Hi,
>
> Your models are having problems right from the first step. Have you regenerated your starting model with the  new mesa version or are you starting with a model made with 10108?
>
> Rob
>
> On Wed, 24 Mar 2021 at 20:29, Arman Aryaeipour via Mesa-users <mesa-users at lists.mesastar.org> wrote:
> Dear Mesa-users,
>
> I've recently migrated over to mesa-r15140 from mesa-r10108 for modelling nova outbursts.
> In these models, I use the other_D_mix hook routine to implement some mixing between the white dwarf and its envelope when the maximum temperature reaches 10^8 K. This mixing is initially only around the white dwarf and envelope interface, and slowly extends out further into the white dwarf and envelope over the course of a few hundred seconds.
>
> When this mixing was carried out using mesa-r10108, the model had no problem converging and evolved through the mixing phase I implemented. However, with mesa-r15140 the model quickly runs into convergence issues after mixing begins and the timestep goes to zero. I've attached the terminal_output.txt file which contains MESAs output from when I start mixing, with report_solver_progress turned on. I've also provided my inlist.
>
> I would be grateful if someone could explain to me what changes in the new version of MESA cause the convergence problems once I begin mixing, and if there is a way I can change these settings to revert them back to how they were in mesa-r10108.
>
> Many thanks in advance!
>
> All the best,
> Arman Aryaeipour
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