[mesa-users] artificial viscosity

jingluan at caltech.edu jingluan at caltech.edu
Sun Jan 1 23:49:38 EST 2012

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 :-)


> Hi Jing,
> On Jan 1, 2012, at 11:06 AM, jingluan at caltech.edu wrote:
>> I am studying the artificial viscosity formulations in MESA. Is there
>> some
>> published reference for the artificial viscosity in MESA please?
> The mesa implementation of artificial viscosity has NOT been carefully
> tested,
> but you are welcome to play with it and let us know how it goes.
> Just understand that for cases with shocks, mesa has NEVER been verified.
> So if it by some chance it happens to produce a reasonable result, it will
> be a fluke.
> There has been a lot of talk about doing full hydrodynamics with shocks in
> mesa,
> but the talk hasn't turned into code yet.  ;-(
> Dave Arnett and I have scribbled at the blackboard about how to do
> explicit hydro
> in mesa -- perhaps something will come of that by summer.  Both of us
> would
> like very much to see it happen, but there are lots of other things
> competing for
> our time.
> For what it is worth, the current implementation of artificial viscosity
> in mesa follows
> the description in this old KEPLER paper:
> Good luck,
> Bill

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