[Mesa-users] Rotation flags

[Rob Farmer]

Hi
When changing the state (say between a non-rotating model and one that
rotates) we break the change up over num_steps_to_relax pseudo time steps
(pseudo as we turn off certain physical processes while making the change).
We make a small change to the model each pseudo time step rather than
trying to change the model to the final state in one go.

When running models with the relax routine pick a number, say 50, if the
model get though the relax process then continue, if not try a larger
number of steps.

Rob


On 9 April 2018 at 09:59, Roque Caballero Navarro via Mesa-users <
mesa-users at lists.mesastar.org> wrote:

> Dear Francis,
>
>    Many thanks for the details. Now it's much clearer to me.
>
>    One additional question regarding the parameter "num_steps_to_relax_rotation".
> I've seen several parameters similar to this in form "num_steps_to_relax...."
> What are they used for?
>
> Kind regards,
>
> Roque
> ------------------------------
> *De:* Francis Timmes <fxt44 at mac.com>
> *Enviado:* sábado, 7 de abril de 2018 15:04
> *Para:* Roque Caballero Navarro
> *Cc:* Frank Timmes; mesa-users at lists.mesastar.org
> *Asunto:* Re: [Mesa-users] Rotation flags
>
> hi roque,
>
> the default values are
>
> new_rotation_flag = .false.
> change_rotation_flag = .false.
> change_initial_rotation_flag = .false.
>
> for now, consider the first two controls.
> to activate rotation
>
> change_rotation_flag = .true.
> new_rotation_flag = .true.
>
> to deactivate rotation after it has been turned on
>
> change_rotation_flag = .true.
> new_rotation_flag = .false.
>
> to leave rotation in whatever on/off state it is in
>
> change_rotation_flag = .false.
>
> these two controls enable one to alter a model
> at the start of a run (./rn) or after a restart (./re).
> controls that only apply to the first model have ‘initial’
> in their names and are ignored for restarts, for example
> change_initial_rotation_flag.
>
> there is also a family of controls that will automatically change the
> flags for you.
> for example, to activate rotation when the model star is near the
> main-sequence:
>
> ! turn on rotation near zams
>       near_zams_relax_omega_div_omega_crit = .true.  ! turn on rotation
> at zams
>       num_steps_to_relax_rotation = 100              ! this number steps
> in the relaxation to the desired value
>       new_omega_div_omega_crit = 0.50d0              ! desired zams value
> of rotation
>
>
> clearer?
>
> fxt
>
>
>
>
> > On Apr 7, 2018, at 2:43 AM, Roque Caballero Navarro via Mesa-users <
> mesa-users at lists.mesastar.org> wrote:
> >
> > Dear all,
> >
> >     I'm trying to understand the use of the rotation flags, in
> particular the following ones:
> >
> > new_rotation_flag
> > change_rotation_flag
> > change_initial_rotation_flag
> >
> >     According to MESA documentation:
> >
> > "rotation is enabled only if rotation_flag is true new_rotation_flag is
> only used if change_rotation_flag is true if change_rotation_flag true,
> then change rotation_flag to new_rotation_flag. NOTE: why 2 flags? because
> I want 3 options:set true, set false, and leave it alone. there are of
> course other ways to get 3 options, but this is what we have."
> >     I've been doing several examples but I'm not able to figure out how
> the mentioned flags related to each others and when it's intended to use
> them. I'd highly appreciate a bit of light in this aspect.
> >
> >     Many thanks in advance.
> >
> > Kind regards,
> >
> > Roque
> >
> >
> >
> >
> >
> > _______________________________________________
> > mesa-users at lists.mesastar.org
> > https://lists.mesastar.org/mailman/listinfo/mesa-users
> >
>
>
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