mesa-users] Hydro convergence failure at end of main sequence.

[Aaron Dotter]

Hi Sam,

I am using MESA version 2664 (compiled with ifortran 11.1) on Ubuntu 10.04
> to run a 20Mo model up to collapse, but at the end of the main sequence I
> get an error "hydro_failed_to_converge". I have tried this with two
> different timestep parameters and attach the inlists for both runs - maybe
> these values for varcontrol are inappropriate?
>

I expect that the setting you're imposing on the composition variables is
too tight.  I tried the run in your inlist with all set to 10 and it did
indeed fail after about 2400 models.  It's putting too many zones in around
the edge of the core and that's causing artificial mixing--so the main
sequence never ends.

I commented out the varcontrol_* lines (so I just use the default values)
and it runs through to the end of the main sequence with no problem.  Not
sure how far it will go after that!  The default values are reasonably well
tuned, which isn't to say that they will always work for any kind of
problem, but they should be good for H and He burning at most masses 0.1 <
Msun < 100 (?).


> As you can see from the inlists, I am also using the Dutch RGB and AGB wind
> scheme but there is no mass loss on the main sequence - is there a parameter
> for this?
>

As with most wind formulas, the "Dutch" version has an adjustable parameter
that is zero by default (no mass loss).  To set it, you need to include the
following, with your value instead of zero:

      RGB_wind_scheme = 'Dutch'
      Dutch_wind_eta = 0d0

Inlist_standard has all the names of all the etas that correspond to the
different wind schemes.

One last note, I see that you are doing set_uniform_initial_composition in
star_job and initial_z in controls.  It's not necessary to do both.  In
fact, MESA should warn you if you do because you could input conflicting
values.  set_uniform_initial_composition will set all the composition
variables you need in a given run.

Best wishes,
Aaron
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