[Mesa-users] Rotation flags

[Roque Caballero Navarro]

Hi Rob,

   Now it's clear. Many thanks for your support.

Kind regards,

Roque
________________________________
De: Rob Farmer <r.j.farmer at uva.nl>
Enviado: lunes, 9 de abril de 2018 8:14
Para: Roque Caballero Navarro
Cc: Francis Timmes; mesa-users at lists.mesastar.org
Asunto: Re: [Mesa-users] Rotation flags

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<mailto: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<mailto: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<mailto: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<mailto: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<mailto:mesa-users at lists.mesastar.org>
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>


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