[Mesa-users] convergence problems of a white dwarf post entropy relaxation

[Francis Timmes]

imposing a chemical profile on a hot wd and letting it evolve
is standard fare in some parts of the wd seismology community.
one can explore this approach in mesa by experimenting with 
josiah schwab's wd_builder https://github.com/jschwab/wd_builder .
i've found building such an ab initio wd to be a lot more useful
that the double relation approach being tried.

once such an out of thermal equilibrium wd starts evolves a few 
thermal timescales and begins sliding down the cooling track, it largely
forgets thermodynamic-wise how it got there. that is, i suspect the 
initial entropy profile does not matter much.

fxt




> On Nov 28, 2020, at 2:14 PM, Akaash Conhye <ac01283 at surrey.ac.uk> wrote:
> 
> Hi Francis,
> 
> What im trying to do is impose both chemical and entropy profiles and watch the white dwarf cool.
> 
> Thanks 
> 
> Akaash
> From: Francis Timmes <fxt44 at mac.com>
> Sent: 28 November 2020 20:42
> To: Conhye, Akaash (UG - Physics) <ac01283 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 of a white dwarf post entropy relaxation
>  
> hi akaash,
> 
> let's take a step back. at high-level, what are you trying to accomplish?
> impose a chemical profile on a white dwarf and then watch the white dwarf cool?
> 
> fxt
> 
> 
> 
> 
> 
> 
> > On Nov 27, 2020, at 1:11 PM, Akaash Conhye via Mesa-users <mesa-users at lists.mesastar.org> wrote:
> > 
> > Hi all,
> > 
> > I'm trying to relax the entropy profile of a white dwarf from 3d hydrodynamic simulations (which used a helmholtz EOS without colomb corrections) but i run into convergence problems once the white dwarf has relaxed and begins its first real time evolution step. the white dwarf has a nickel-56 envelope and the star has a total mass of 0.6 solar masses. The terminal output is shown at the end.
> > 
> > I started by first relaxing the composition profile, saving this model, then relaxing entropy afterwards. the relative error I have is ~0.1526. The template im using is wd_cool_0.6M. It could be that I have some obvious improper physics in my inlist so I've attached a copy of it. the things ive tried to change are available to see on "inlist_wd_cool_0.6M" (my changes are denoted with !!, single ! are default comments) but if you find this distracting, I've also attached a copy of the inlist without the comments named "inlist_wd_cool_0.6M_uncommented".
> > ...
> > Terminated relax because of max_model_number instead or relax_time
> >  net name approx21.net
> >  use_gold_tolerances T
> >  do_element_diffusion T
> >                                       atm_option: T_tau
> >  species
> >      1   neut
> >      2   h1
> >      3   prot
> >      4   he3
> >      5   he4
> >      6   c12
> >      7   n14
> >      8   o16
> >      9   ne20
> >     10   mg24
> >     11   si28
> >     12   s32
> >     13   ar36
> >     14   ca40
> >     15   ti44
> >     16   cr48
> >     17   cr56
> >     18   fe52
> >     19   fe54
> >     20   fe56
> > 21   ni56
> > 
> >  kappa_file_prefix gs98
> >  kappa_lowT_prefix lowT_fa05_gs98
> >                                         OMP_NUM_THREADS          16
> > 
> > 
> >  retry     130
> >  retry     130
> > backup     130
> >  retry     130
> >  retry     130
> > backup     130
> >  retry     130
> >  retry     130
> > backup     130
> >  retry     130
> >  retry     130
> > backup     130
> >  retry     130
> >  retry     130
> > backup     130
> >  retry     130
> >  retry     130
> > backup     130
> >  retry     130
> >  retry     130
> > backup     130
> >  retry     130
> >  retry     130
> > backup     130
> > backup     130
> >  retry     130
> >  retry     130
> > backup     130
> >  retry     130
> >  retry     130
> > backup     130
> >  retry     130
> >  retry     130
> > backup     130
> >  retry     130
> >  retry     130
> > backup     130
> >  retry     130
> >  retry     130
> > backup     130
> >  retry     130
> >  retry     130
> > backup     130
> >  retry     130
> >  retry     130
> > backup     130
> >  retry     130
> >  retry     130
> > backup     130
> > 
> > terminated evolution: dt_is_zero
> > 
> > termination code: dt_is_zero
> > DATE: 2020-11-27
> > TIME: 18:47:38
> > 
> > 
> > Thanks for your help,
> > 
> > Akaash
> > 
> > 
> > <inlist_wd_cool_0.6M><inlist_wd_cool_0.6M_uncommented>_______________________________________________
> > mesa-users at lists.mesastar.org
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