[mesa-users] surface abund.

[Earl Bellinger]

What is a sensible range of values for surface_avg_abundance_dq?

I'm running into a problem right now where I occasionally encounter
abundance discontinuities at the surface when I use an Eddington atmosphere
with atomic diffusion enabled. First the metals will drain continuously
from the surface, giving surface_h1 = 1. Then randomly, in a single time
step, 25% of the surface will become mixed with other elements again. I've
tried decreasing mesh_delta_coeff down to 0.1 and the time stepping down to
1d5 but it doesn't help any. Any suggestions would be appreciated.

Best regards,
Earl Bellinger
Stellar Ages & Galactic Evolution Group
Max-Planck-Institut für Sonnensystemforschung

On Sun, Feb 14, 2016 at 9:45 PM, Bill Paxton <paxton at kitp.ucsb.edu> wrote:

>
> On Feb 14, 2016, at 12:31 PM, Bruno Lustosa wrote:
>
> > Thank you Bill. then it means that I define the "size / length" of my
> surface in relation to star as a whole? I include it then Control?
>
> correct.  the 'surface_avg_abundance_dq' is the fraction of mass
> considered surface to the total mass of the model.
>
> searching the webpage http://mesa.sourceforge.net/controls_defaults.html
> for 'surface_avg_abundance_dq' will tell you that the default is set to
> 1d-8.   You can revise that in your inlist if you wish.
>
> if you'd like to specify the thickness of the surface in other units, then
> you will need to add a few lines to your run_star_extras to define a new
> history entry.   not as trivial as using something that is built in, but it
> gives you the ability to get exactly what you want at a relatively small
> cost once you learn how to do it -- e.g., see
> http://mesa.sourceforge.net/run_star_extras.html#toc-1-2.
>
> b
>
>
>
> >
> > Bruno L. Moura
> > Instituto Federal do Rio Grande do Norte - IFRN
> > +55(84)99991-9550
> >
> >> Em 14 de fev de 2016, às 14:12, Bill Paxton <paxton at kitp.ucsb.edu>
> escreveu:
> >>
> >> Hi,
> >>
> >> Yes, to include surface be9 in the history, just add it to the list as
> follows
> >>
> >> surface be9
> >>
> >> Or, if you prefer,
> >>
> >> log_surface be9
> >>
> >> If at some step along the way, be9 is not in the current net, it will
> have abundance 0 as expected.
> >>
> >> The definition of "surface" is set by the control
> "surface_avg_abundance_dq" -- i.e., it isn't limited to the outermost cell.
> >>
> >> Cheers,
> >> Bill
> >>
> >>
> >>
> >>
> >>> On Feb 14, 2016, at 6:50 AM, Bruno Lustosa wrote:
> >>>
> >>> Hello everyone
> >>>
> >>> I wonder if the history_columns.list outputs I can include any surface
> abundance? For example, if I want plenty of any other element is just
> simply I put surface be9?
> >>>
> >>> Cheers
> >>>
> >>> Bruno
> >>>
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