[Mesa-users] Equivalents to use_zero_dLdm_outer_BC in newer MESA releases

[Ebraheem Farag]

Hi Benjamin,

This boundary condition was probably removed during some pruning (from
r15140 -> r21.12.1, one of the biggest internal clean ups of the code base
since its inception) as it was not being used. You can probably reimplement
it using a use_other_surface_PT hook in the run_star_extras.f90 similar to
how the boundary conditions on the conductive flame test suite are
implemented, see
https://docs.mesastar.org/en/release-r24.03.1/test_suite/conductive_flame.html
.

You just need to look into "./private/hydro_eqns.f90" in r15140, find "
*subroutine* set_zero_dL_dm_BC" and paste it into your
use_other_surface_PT hook
in the run_star_extras.f90 and tweak accordingly.

I hope this helps. If you feel this outer boundary condition is important
and should be reimplemented into the code base as a default option, I
suggest opening an issue thread on the MESA github
https://github.com/MESAHub/mesa/issues to make your case :).

-EbF

On Tue, Jul 9, 2024 at 9:34 AM Benjamin Herfray via Mesa-users <
mesa-users at lists.mesastar.org> wrote:

> Hello MESA users,
>
> I've been trying to run simulations of stellar winds during type-I X-ray
> bursts using version r24.03.1. In order to try to counter problems with
> density inversions developing near the outer layers of the atmosphere I
> would like to impose boundary conditions on the luminosity—specifically, I
> would like to impose dL/dm = 0 at the outer boundary.​ This is similar to
> the methods described in Yu & Weinberg, 2018 (
> https://doi.org/10.3847/1538-4357/aad045
> <https://urldefense.com/v3/__https://doi.org/10.3847/1538-4357/aad045__;!!IKRxdwAv5BmarQ!bk6TKa_fsuOzH32gDnHkWkhQLjQmM6bCZbZybr_JO604FPuhKJvQSzGk7VrTAHXCwIi75agxEARks4mV3G_dXHZLO6M0iw$>)
> and Guichandut & Cumming, 2021 (https://doi.org/10.3847/1538-4357/ace43c
> <https://urldefense.com/v3/__https://doi.org/10.3847/1538-4357/ace43c__;!!IKRxdwAv5BmarQ!bk6TKa_fsuOzH32gDnHkWkhQLjQmM6bCZbZybr_JO604FPuhKJvQSzGk7VrTAHXCwIi75agxEARks4mV3G_dXHaJQJjRnA$>)
> who used older versions of MESA.
>
> Older versions of MESA (I believe up to r15140) have the control
> use_zero_dLdm_outer_BC to impose L(1) = L(2), however this was removed in
> subsequent versions with no explanation of the change in the changelog.
>
> Does anyone know why this was removed, and is there a combination of
> controls present in the current version of MESA that I can use to have the
> equivalent effect as use_zero_dLdm_outer_BC? Or would I have to implement
> this as a custom condition through run_star_extras?
>
> Thank you,
> Benjamin Herfray
> _______________________________________________
> mesa-users at lists.mesastar.org
>
> https://urldefense.com/v3/__https://lists.mesastar.org/mailman/listinfo/mesa-users__;!!IKRxdwAv5BmarQ!bk6TKa_fsuOzH32gDnHkWkhQLjQmM6bCZbZybr_JO604FPuhKJvQSzGk7VrTAHXCwIi75agxEARks4mV3G_dXHZtuWppvQ$
>
>
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