[Mesa-users] other_torque subroutine computed twice

[Pablo Marchant]

Setting premix_omega to .false. means angular momentum transport will be
done before the newton solver, so it might not solve your problem. One
alternative you could do is just multiply your jdot by 2 (just a hack), or
compute at the end of the step (in extras_finish_step) the value of
dMrad/dt and use that in the following step. You can do that by storing it
in the xtra variables, for instance "s% xtra(1) = expression for dMrad/dt"
in extras_finish_step, and then just accessing s% xtra(1) in your torque
subroutine.

Cheers

On Thu, Nov 26, 2020 at 3:35 PM Saldana-Munoz, Miriam Rosario (9830xxx) <
miriam.saldana-munoz at edu.uni-graz.at> wrote:

> Thank you Pablo,
>
>
> I had a real problem applying a torque which includes dMrad/dt (i.e. the
> mass variation of the radiation shell during a time step), by computing the
> difference between the actual Mrad and the last saved Mrad_old.
> Therefore, the second time, my_other_torque gave always the result 0 for
> this difference.
>
>
> But now if extra_jdot is not computed the second time because the
> inclusion of the if statement, extra_jodot would be transported only for
> half of the time and the results could not be valid either. In this case, would
> it be a good idea to set premix_omega to false?
>
>
> Cheers,
>
> Miriam
> ------------------------------
> *Von:* Pablo Marchant <pamarca at gmail.com>
> *Gesendet:* Donnerstag, 26. November 2020 14:45
> *An:* Saldana-Munoz, Miriam Rosario (9830xxx)
> *Cc:* mesa-users at lists.mesastar.org; Razinkov, Andriy Vasylhovych
> (1313xxx)
> *Betreff:* Re: [Mesa-users] other_torque subroutine computed twice
>
> Hi Miriam,
>
> this behavior is normal. Angular momentum transport is split from the
> general newton solver for the rest of the structure equations. By default,
> it is split such that mixing is computed for dt/2 before the newton solver,
> and dt/2 after the newton solver. This is the reason why you see two calls
> each step. Being more specific, this behavior is controlled by the option
> premix_omega, which is true by default.
>
> Cheers
>
> On Thu, Nov 26, 2020 at 2:36 PM Saldana-Munoz, Miriam Rosario (9830xxx) <
> miriam.saldana-munoz at edu.uni-graz.at> wrote:
>
>> Dear mesa-users,
>>
>>
>> I have developed my own other-torque subroutine. The running was
>> successful but as the results were not convincing I did some debugging.
>> I have realised that MESA computes my_other_torque twice for every
>> model_number.
>>
>>
>> The problem is already solved by introducing an if statement, but I would
>> like to know if this kind of behaviour is normal (version MESA ​12778)
>>
>>
>> Thank you very much in advance.
>>
>>
>> Miriam
>> _______________________________________________
>> mesa-users at lists.mesastar.org
>> https://lists.mesastar.org/mailman/listinfo/mesa-users
>>
>>
>
> --
> Pablo Marchant Campos
> M.Sc on Astrophysics, Universidad Católica de Chile
> PhD on Astrophysics, Argelander-Institut für Astronomie, Universität Bonn
>


-- 
Pablo Marchant Campos
M.Sc on Astrophysics, Universidad Católica de Chile
PhD on Astrophysics, Argelander-Institut für Astronomie, Universität Bonn
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