[Mesa-users] Unable to change temperature gradient when atomic diffusion is turned on

[Evan Bauer]

After digging around for a bit, I have a correction on the timeline of the bug I was referring to...

The bug was introduced in some dev versions between 12778 and 15140, but was fixed in svn revision 14984, so it never did impact any release versions.

Cheers,
Evan

> On Aug 23, 2021, at 4:19 PM, Evan Bauer <evan.bauer.astro at gmail.com> wrote:
> 
> Hi Joey,
> 
> What MESA version are you using? In 11701 (and other release versions), when diffusion is on, there is a call to update_vars after diffusion updating things to reflect the new composition, but it should also be setting skip_mixing_info = .true. for that call after diffusion. So the lines you've quoted in your email should be skipped for that particular call to update_vars, and diffusion should have no impact on adjust_mlt_gradT_fraction.
> 
> There WAS a bug in some dev versions (soon after 15140) that broke some of this logic, but as far as I recall, that bug was fixed fairly promptly and never impacted a release version. So if you're using a dev version, can you point me to the commit number/hash? I should probably be able to help you diagnose a fix.
> 
> Cheers,
> Evan
> 
> 
>> On Aug 23, 2021, at 12:26 PM, Joey Mombarg <joey.mombarg at kuleuven.be> wrote:
>> 
>> Dear mesa-users,
>> 
>> I am trying to change the temperature gradient to the adiabatic one in the overshoot zone using the run_star_extras routine from Michielsen et al. 2019, where also atomic diffusion and radiative levitation are turned on. While mesa does indeed report that s% adjust_mlt_gradT_fraction(k) = 1 just before calling adjust_gradT_fraction (around line 668 in star/private/mlt_info.f90, r11701), it seems to be overwritten later in star/private/hydro_vars.f90, around line 565:
>> 
>>           if (.not. skip_mixing_info) then
>>              s% mixing_type(1:nz) = no_mixing
>>              s% adjust_mlt_gradT_fraction(1:nz) = -1
>>           end if
>> 
>> This condition seems to be fulfilled during the main-sequence evolution when atomic diffusion is turned on. I was wondering why adjust_mlt_gradT_fraction is changed to -1 here, and if there are any objections in removing this behaviour for this particular case? 
>> 
>> Kind regards,
>> Joey
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>