[mesa-users] Timestep control

[Mathieu]

Actually, I was more worried about the thermal timescale.
I just listed some timescales that came to my mind in my previous email, 
because intuitively I would expect MESA to check that the timestep is 
smaller than all the relevant timescales explicitly, but it is not what 
it doing right now.

Thanks a lot!

Mathieu

On 08/26/2014 08:16 PM, Josiah Schwab wrote:
> In-reply-to: <3A079F20-5FCB-4940-8B87-5996B3E5C42C at kitp.ucsb.edu>
>
> Hi Bill,
>
>> I stated it for mass loss since Mathieu had asked for a limit rated to
>> mass loss timescale.
>> For your case, I think we are already covered with "delta_lg_star_mass_limit",
>> although perhaps the name isn't the best.   Note that we also have limits for
>> the change in Mdot ("delta_mdot_limit").
> Thanks for reminding me of this control.
>
> Mathieu's case is also covered by this control, which enforces
>
>      abs(log10_cr(s% mstar/s% mstar_old)) < delta_lg_star_mass_limit
>
> which for small mass changes is
>
>      abs(dt*Mdot) / (M*ln(10)) < delta_lg_star_mass_limit
>
> and so is equivalent (up to a dimensionless constant)
>
>      dt / (M / abs(Mdot) < ln(10) * delta_lg_star_mass_limit
>
> to the new control.
>
>
> As part of my campaign for fewer MESA controls,  I say either:
>
>    (1) eliminate delta_lg_star_mass_limit in favor of
>    dt_div_dt_mass_change
>
>    (2) just use the existing control
>
>
> I don't like adding a semi-redundant control.
>
> Josiah
>
> P.S.  I vote* (1), but maybe I'm biased, because every time I use
> delta_lg_star_mass_limit, I always screw up that ln(10) :)
>
> * Not that this is a democracy :)
>
> ------------------------------------------------------------------------------
> Slashdot TV.
> Video for Nerds.  Stuff that matters.
> http://tv.slashdot.org/
> _______________________________________________
> mesa-users mailing list
> mesa-users at lists.sourceforge.net
> https://lists.sourceforge.net/lists/listinfo/mesa-users