[mesa-users] exploring vibrations in mesa/star models
fxt44 at mac.com
Mon Jan 2 18:09:11 EST 2012
it appears to me that you are interested in follow sound
waves bouncing around. if so, i think you should be using
a courant timestep limited explicit hydrodynamics code
to accurately follow this behavior. in my opinion,
mesa is not (yet, perhaps) the right tool for the job.
On Jan 2, 2012, at 9:56 AM, jingluan at caltech.edu wrote:
> On Jan 1, 2012, at 8:49 PM, jingluan at caltech.edu wrote:
>> we start with a perturbed initial model. Physically
>> the star should keep vibrating for a thermal (kh_timescale) time scale,
>> but mesa damped the vibration in about 1 vibration period
> Does anyone have suggestions for Jing?
> All I can think of is to set max_years_for_timestep
> to make sure the timestep is limited
> to be much smaller than the period of vibration.
> But I don't have any direct experience with this
> sort of thing, so perhaps someone else has
> better ideas.
Thank you, Bill. We have tried to limit the maxtimestep to be e.g. 1/20 of
the vibration time scale. However, MESA keeps shrinking the real time step
model by model so that the first half of the vibration period never ends.
> Hi Bill,
> Is there any other method except artificial viscosity to help hydro-static
> convergence please? We start with a perturbed initial model. Physically
> the star should keep vibrating for a thermal (kh_timescale) time scale,
> but mesa damped the vibration in about 1 vibration period. I checked the
> hydro_eqn.f and turned off the artificial viscosity, but the vibration
> still got damped in the same manner. By reading the hydro_eqn.f file, I
> did not find any other trick except artificial viscosity. Did I miss
> something? Does mesa use some other technique to damp vibration please?
> Thank you so much :-)
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