[mesa-users] Use of other_am_mixing

[Bill Wolf]

Hi all,

I’ve been trying to use other_am_mixing to experiment with viscosities in MESA 7624. In the null file (star/other/other_am_mixing.f90), an example is given for adding a constant viscosity to each cell:

         ! for example, you can add uniform extra diffusion as follows: 
         
            ! nu_additional = 3d4 ! cm^2/s
            ! forall (k=1:s% nz) s% am_nu(k) = s% am_nu(k) + nu_additional

If I try this, the compiler tells me that am_nu is not a part of the star_info structure, and indeed, it is not [anymore?]. So I tried to set s% am_nu_rot. This “works” in that the values are changed, but it has no effect on the structure since by the time other_am_mixing is called (currently in update_rotation_mixing_info in star/private/mix_info), am_nu_rot and am_nu_non_rot have already been used to update the real vectors of importance: am_nu_omega and am_nu_j.

The main takeaway is that, as far as I can tell, other_am_mixing should be used primarily to set am_nu_omega and am_nu_j. Perhaps the comments in star/other/other_am_mixing.f90 should also indicate this.

Just wanted to get that out there so someone else doesn’t foolishly try to change the wrong viscosities.

Regards,

Bill
________________________
William Wolf
wmwolf at physics.ucsb.edu

UCSB Department of Physics