[Mesa-users] Doubt on overshoot parameters

[Rob Farmer]

Hi,
Your second answer is the right path. To keep the same amount of
overshooting then your new f values needs to be your old f value + your new
f0 value. So you'd want to set your f values to 0.019 with f0's being
0.001. this is because we start the overshoot a distance f0 in from the
convective edge, so in total the new overshoot extends a distance f-f0.

Rob


On Sun, 9 Dec 2018, 14:45 anne.thoul at uliege.be <anne.thoul at uliege.be wrote:

> Dear Pedro,
>
>
> Your last example is the right way to do it.
>
> >>     overshoot_f_above_burn_h_core = 0.018
> >>     overshoot_f_above_burn_h_shell = 0.018
> >>     overshoot_f_below_nonburn_shell = 0.018
> >>
> >>     overshoot_f0_above_burn_h_core = 0.001
> >>     overshoot_f0_above_burn_h_shell = 0.001
> >>     overshoot_f0_below_nonburn_shell = 0.001
>
> In case of doubt, you can always look at the examples in the test_suite.
> For example the inlist of the case « inlist_7M_prems_to_AGB"  has the
> following setup for overshooting to cover all situations:
>
>       overshoot_f_above_nonburn_core = 0.014
>       overshoot_f_above_nonburn_shell = 0.014
>       overshoot_f_below_nonburn_shell = 0.014
>       overshoot_f_above_burn_h_core = 0.014
>       overshoot_f_above_burn_h_shell = 0.014
>       overshoot_f_below_burn_h_shell = 0.014
>       overshoot_f_above_burn_he_core = 0.014
>       overshoot_f_above_burn_he_shell = 0.014
>       overshoot_f_below_burn_he_shell = 0.014
>       overshoot_f_above_burn_z_core = 0.014
>       overshoot_f_above_burn_z_shell = 0.014
>       overshoot_f_below_burn_z_shell = 0.014
>
>       overshoot_f0_above_nonburn_core = 0.004
>       overshoot_f0_above_nonburn_shell = 0.004
>       overshoot_f0_below_nonburn_shell = 0.004
>       overshoot_f0_above_burn_h_core = 0.004
>       overshoot_f0_above_burn_h_shell = 0.004
>       overshoot_f0_below_burn_h_shell = 0.004
>       overshoot_f0_above_burn_he_core = 0.004
>       overshoot_f0_above_burn_he_shell = 0.004
>       overshoot_f0_below_burn_he_shell = 0.004
>       overshoot_f0_above_burn_z_core = 0.004
>       overshoot_f0_above_burn_z_shell = 0.004
>       overshoot_f0_below_burn_z_shell = 0.004
>
> Cheers
>
> Anne
>
>
>
> > Le 9 déc. 2018 à 14:04, Pedro Nuno David Gomes via Mesa-users <
> mesa-users at lists.mesastar.org> a écrit :
> >
> > Dear MESA users,
> >
> > I have a doubt on the overshoot parameters I was hoping you could help
> me clarify. I'm sure this is a very simple doubt, but I can't wrap my head
> around it.
> >
> > I have an inlist of a previous MESA release (release 7456) with the
> following controls regarding the overshooting,
> >
> >     overshoot_f_below_nonburn = 0.018
> >     overshoot_f_above_burn_h = 0.018
> >     overshoot_f_above_burn_he = 0.018
> >
> > From what I understood, using these controls one establishes that
> overshoot occurs at a distance 0.018*H from the boundaries of convective
> regions, with H being the scale height. Right?
> >
> > Now, I was trying to run the same controls in the latest MESA release
> but I got an error: "Fortran runtime error: Cannot match namelist object
> name overshoot_f_below_nonburn".
> >
> > So, the previous controls changed with posterior releases. I'm having
> some doubts understanding how to implement these controls in the current
> release. At first I simply thought about replacing them directly with (what
> I think are) the updated controls,
> >
> >     overshoot_f_above_burn_h_core = 0.018
> >     overshoot_f_above_burn_h_shell = 0.018
> >     overshoot_f_below_nonburn_shell = 0.018
> >
> > (I'm not considering helium burning regions because I'm only interested
> in analysing the lower Red Giant Branch). But when I run MESA I get an
> error: "ERROR: when using overshooting above, must set f0_above > 0".
> >
> > From what I read on the controls defaults, namely
> >
> >     "The switch from convective mixing to overshooting happens at a
> distance f0*Hp into the convection zone
> >     (...) where Hp is the pressure scale height at that location.",
> >
> > I also have to define f0. So, given this explanation, what I thought I
> had to do was replace f with f0,
> >
> >     overshoot_f0_above_burn_h_core = 0.018
> >     overshoot_f0_above_burn_h_shell = 0.018
> >     overshoot_f0_below_nonburn_shell = 0.018
> >
> > And in this case MESA runs. However, I'm not sure if this is the way -
> from what I read after, namely
> >
> >      "for example, if you want overshooting of 0.2 scale heights beyond
> the normal edge, you might want
> >       to back up 0.05 scale heights to get the diffusion coeff from near
> the edge and then go out by 0.25
> >       scale heights from there to reach 0.2 Hp beyond the old boundary.
> In the inlist this would mean setting
> >       the “f0” to 0.05 and the “f” to 0.25."
> >
> > I have to define in the inlist controls with f and f0 simultaneoulsy;
> so, from my understanding, this would mean writting, for instance,
> >
> >     overshoot_f_above_burn_h_core = 0.018
> >     overshoot_f_above_burn_h_shell = 0.018
> >     overshoot_f_below_nonburn_shell = 0.018
> >
> >     overshoot_f0_above_burn_h_core = 0.001
> >     overshoot_f0_above_burn_h_shell = 0.001
> >     overshoot_f0_below_nonburn_shell = 0.001
> >
> > Is any of these the right way, or am I missing something? If this is the
> case, could you help me understand how to replace the previous controls
> with these values?
> >
> > Thank you for your attention. Regards,
> >
> > Pedro
> > _______________________________________________
> > mesa-users at lists.mesastar.org
> > https://lists.mesastar.org/mailman/listinfo/mesa-users
> >
>
> _______________________________________________
> mesa-users at lists.mesastar.org
> https://lists.mesastar.org/mailman/listinfo/mesa-users
>
>
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