[mesa-users] extra heat source in mesa star

Bill Paxton paxton at kitp.ucsb.edu
Thu Dec 9 13:32:24 EST 2010

damn -- there's bug in that little code fragment I just sent.   You'll need to set extra_heat(k) to 0 as in the fix below.
Just proving once again that nothing is too simple to have a bug!   Maybe there are still more in there.   Let me know.


On Dec 9, 2010, at 10:26 AM, Bill Paxton wrote:

> Hi Yevgeni,
> As you know, there are a couple of simple schemes for adding energy, either uniformly by setting the 'extra_power_source' control or near surface to model irradiation by setting 'flux_for_hemisphere_irradiation'.    But your case goes beyond those.
> The general scheme for adding extra heat involves writing a few lines of code.  Look at star/public/other_energy.f.   The routine 'do_other_energy' is called from inside star to set the vector 's% extra_heat'.  The value of s% extra_heat(k) is in ergs/g/sec; it will be added to the energy generation term for cell k along with nuclear reactions.  You'll want to change that to set extra_heat(k) according the your rule.  You can access information such as the radius for the outer edge of cell k as s% r(k).   Here is a little example that turns on extra heat depending on radius.
>       subroutine do_other_energy(s, ierr)
>          ! set s% extra_heat(k) to ergs/g/sec average for cell k
>          use const_def, only: Rsun
>          type (star_info), pointer :: s
>          integer, intent(out) :: ierr
>          integer :: k
>          ierr = 0
>          ! here is an example of calculating extra_heat for each cell.
>          do k = 1, s% nz
>             if (s% r(k) > 0.7*Rsun .and. s% r(k) < 0.9*Rsun) then
>                s% extra_heat(k) = 1d3*exp(-10*(s% r(k) - 0.8*Rsun)**2) ! 10^3 erg/g/s at peak
				s% extra_heat(k) = 0
>             end if
>          end do
>          s% d_extra_heat_dlnd(:) = 0 ! obsolete and will go away in future release
>          s% d_extra_heat_dlnT(:) = 0 ! obsolete and will go away in future release
>       end subroutine do_other_energy
> After you edit other_energy.f, change to the mesa/star/test directory and do 
> ./mk
> ./ck
> ./export
> The ./ck should not produce any output (that means it is okay).
> The ./export makes your changes available to your work directories.
> In the not-too-distant future I'll be changing the way this works to make it a bit easier (by using the Fortran2003 feature of having pointers to procedures as elements of derived types).  But until then, you'll need to go through the sequence of edit, make & export from star/test, and then remake and run in your work directory.
> Let me know how it goes!
> Cheers,
> Bill
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