[Mesa-users] do_element_diffusion = .false. != diffusion_class_factor(:) = 0

[Evan Bauer]

Hi Earl,

The class factors should still work when you’re using the full net. You would just need to set as many factors as there are isotopes in 
your net.

Alternatively, if you want fewer lines and you’re happy with every isotope scaling the same way, you could use

      diffusion_SIG_factor = 0d0
      diffusion_GT_factor = 0d0

Those are terms that multiply roughly the “concentration diffusion” and “gravitational settling”, and they apply across the board to all diffusion velocities. I haven’t thoroughly tested using these controls for this purpose, but I’m pretty sure they should work for what you want.

Cheers,
Evan


> On Dec 14, 2017, at 1:34 PM, Earl Bellinger <bellinger at mps.mpg.de> wrote:
> 
> A follow-up question: is there a best way to arbitrarily enhance or inhibit diffusion when using the full net (diffusion_use_full_net)? [That was what led me to try the diffusion_class_factor(:) approach in the first place.] I guess I can make a class for every isotope I'm tracking? 
> 
> Best regards, 
> Earl Bellinger 
> 
> On Thu, Dec 14, 2017 at 8:16 PM, Earl Bellinger <bellinger at mps.mpg.de <mailto:bellinger at mps.mpg.de>> wrote:
> Ah that makes good sense, thanks! 
> 
> Best regards, 
> Earl 
> 
> 
> On Thu, Dec 14, 2017 at 8:00 PM, Aaron Dotter <aaron.dotter at gmail.com <mailto:aaron.dotter at gmail.com>> wrote:
> Hi,
> 
> If you ever need to check what's going on "under the hood" with &controls, there is the option to
> 
> write_controls_info_with_profile
> 
> which will dump the controls namelist into a file of your choosing.  This happens every time a profile is written but would still be useful for checking in this case.
> 
> Aaron
> 
> On Thu, Dec 14, 2017 at 1:47 PM, Evan Bauer <ebauer at physics.ucsb.edu <mailto:ebauer at physics.ucsb.edu>> wrote:
> Hi Earl,
> 
> It looks like your inlist command is only setting the first class factor to 0. That is
>         diffusion_class_factor(:) = 0
> somehow only gets diffusion_class_factor(1) and leaves the rest of them untouched. Since the default number of diffusion classes is five, I think your inlist needs
>         diffusion_class_factor(1) = 0
>         diffusion_class_factor(2) = 0
>         diffusion_class_factor(3) = 0
>         diffusion_class_factor(4) = 0
>         diffusion_class_factor(5) = 0
> 
> Somebody who understands fortran namelists better than me can probably explain exactly why this is happening, but hopefully the above is an adequate solution.
> 
> Cheers,
> Evan
> 
> 
> > On Dec 14, 2017, at 3:58 AM, Earl Bellinger <bellinger at mps.mpg.de <mailto:bellinger at mps.mpg.de>> wrote:
> >
> > Dear mesa-users,
> >
> > I am wondering if someone can help me to understand why turning off
> > element diffusion yields a different result than setting the diffusion
> > factor to 0? I would expect, perhaps naively, for them to yield the
> > same result.
> >
> > Some simple inlists are attached for calculating the first Gyr of
> > evolution for a solar mass track. There's a small difference in
> > several quantities, for example the effective temperature changes from
> > 5643.763 to 5643.913. This is somewhat different from running it with
> > diffusion class factor of 1, which gives Teff of 5643.915.
> >
> > Best regards,
> > Earl Bellinger
> >
> > ---
> > earlbellinger.github.io <http://earlbellinger.github.io/>
> > Earl Bellinger, Ph.D. Candidate
> > Stellar Ages & Galactic Evolution Group
> > Max Planck Institute for Solar System Research
> > <inlist_diff_off><inlist_diff_0><diff_off.data><diff_0.data>
> 
> 
> 
> 

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