[mesa-users] density and sound speed profiles with "ripples" in solar calibration example

[Ana Olímpia]

Hi Bill,


Quick comment: since r is defined at cell boundaries, while csound and
> density are defined at cell centers, you can generate visual ripples in a
> plot by showing values at cell center offset to cell boundary.  To get
> around this, we need to either use the radius at the cell center (called
> rmid) for the x axis, or switch to plotting center values that have been
> interpolated to the cell face (e.g., csound_at_face instead of csound).
>
> Have you done that in the plots you sent?  If not, that would be 1st thing
> to try.


The first thing I did was recompute the acoustic potential with all the
values at cell boundaries: rmid, csound and logRho. It worked fine. The
"ripples" in density and sound speed have disappeared completely. I
attached a file with the all the new figures.


> For your calculations, you might want to do everything at cell boundaries
> -- so for values defined at cell centers, you'll need to interpolate.
> There is a routine to make that easy in star/public/star_lib: it is called
> star_interp_val_to_pt.  It does a monotonic cubic interpolation.
>

Yes, I would like to do everything at cell boundaries also. But here, I
could not finish, I have a problem. Since the radius (or logR) and
csound_at_face I can take directly from profile columns I just need to
interpolate the density. I'm not calling the routine star_interp_val_to_pt
properly. I read this: http://mesa.sourceforge.net/run_star_extras.html and
tried to adapt to this case. Among other things I copied the routine
directly to the run_star_extras.f file and/or added a line
star_interp_val_to_pt = .true. to the inlist_solar, etc...Nothing works. I
was also wondering if to use the routine star_interp_val_to_pt I have to
add new columns to the profile output or it it will just return the
interpolated values of density (temperture and others) at boundaries. This
is for sure very easy to do but I am a bit lost...

In the very first part of the link above, in the section dedicated to
activate the run_star_extras.f file, I noticed that I don't have a line
like this: include 'standard_run_star_extras.inc' inside the file
run_star_extras.f. It looks like the file (standard_run_star_extras.inc)
has been already copied to the run_star_extras.f

>
> When we do the comparison of the star model sound speed profile to the
> data, we use csound_at_face rather than csound --- it makes a huge
> difference.
>

Why is that difference so huge? And why the values at cell boundaries
produce a "better" comparison than the values at cell centers?


Regards and thank you very much in advance!

Ana







>
>
> On Aug 20, 2014, at 5:13 PM, Ana Olímpia wrote:
>
> > Hello all,
> >
> > I am trying to use the solar_calibration example in the test suite
> directory to compute the solar acoustic potential (formula 1 in the
> attached file) with mesa.
> >
> > To do this I just need the radius, the sound speed, and the density
> profiles which I took from the profile.data file of the final model in the
> LOGS directory.
> >
> > I computed this potential, several times before, with the CESAM code but
> I can't reproduce the results with mesa.
> > I decided to compare, step by step, the process of computing the
> potential with MESA and with CESAM. A summary of this comparison is in the
> file AP_with_MESA.
> > In the final plot of the acoustic potential for the Sun, we should be
> able to identify the superadiabatic region, the second Helium ionization
> and the base of the convective zone (figure 8 in the attached file
> AP_with_MESA)
> >
> > I suspect that those "ripples" in figure 2 and 3, respectively in the
> sound speed and density, are responsible for the final result of the
> potential with MESA. I tried to play with the mesh refinement parameters
> but I got always the same final result for the acoustic potential that can
> be seen in figure 8.
> >
> > Why am I getting those "ripples" in the density profile and in the sound
> speed profile?
> >
> > Thank you very much in advance!
> >
> > Ana
> >
> > PS1 - I use exactly the same process to compute the potential with mesa
> and with cesam. The difference is only in the input data: radius, sound
> speed and density.
> >
> > PS2 - Ubuntu 14.04, Mesa version 6794, Mesa SDK version 20140715
> >
> >
> <AP_with_MESA.pdf>------------------------------------------------------------------------------
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>
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