[Mesa-users] Understanding older Mesh_delta coefficient controls for convective boundaries

[Francis Timmes]

hi shaquann,

fortunately the older controls are somewhat self-documenting. say one is using r12778. perusing star/defaults/controls.defaults will show among others

         !### xtra_dist_{above | below}_{lower | upper}_{nonburn | hburn | heburn | zburn}_czb
         ! Increase resolution up to this distance away from the convective zone boundary,
         ! with distance measured in units of the pressure scale height at the boundary.

instead of these older controls one could try to add more resolution around convective boundaries with

https://docs.mesastar.org/en/release-r24.06.1-rc1/reference/controls.html#convective-bdy-weight

fxt





> On Jun 18, 2024, at 2:53 PM, Shaquann Seadrow via Mesa-users <mesa-users at lists.mesastar.org> wrote:
> 
> Hi mesa-users, 
> I am trying to adjust the mesh around the boundaries of non-burning convention zones in massive star models. I wanted to understand how a set of older controls worked so I can figure out how to best mimic them in the r23.05.1 version. I plan to follow the suggestions in the changelog to either use a custom routine or specific mesh_delta coefficient.   
> 
> I wanted to know if anyone could comment on these controls that have been removed for the past couple versions:
> 
>     • xtra_coef_czb_full_{on,off}
>     • xtra_coef_{a,b}_{l,u}_{n,h,he,z}b_czb
>     • xtra_dist_{a,b}_{l,u}_{n,h,he,z}b_czb
>     • xtra_coef_scz_above_{n,h,he,z}b_cz
> Most of this makes sense in terms of scaling the mesh delta, specifying the burning, and specifying the boundary.
> 
> My questions are: 
> Is xtra_dist... setting a limit for which to use the alternate mesh_delta_coef in either the upper or lower boundary? ( eg. everything with those boundaries use a different mesh-delta_coef)
> 
> What is implied by the  'a' , ' b'  extensions in the controls 2 and 3?  
> 
> For control 1, is there a difference between xtra_coef_czb_full_on = 0.0 and xtra_..._full_off = 1.0 and vice versa?
>  
> What is control 4, xtra_coef_scz_above_...cz ? 
> 
> I couldn't find the documentation on versions prior to r15140. As I understand, these controls were deprecated in this release and all those after it. Any help is much appreciated and look forward to your reply. 
> Best, 
> 
> Shaquann 
> 
> -- 
> Shaquann S. Seadrow
> PhD. Candidate
> Dept. of Physics & Astronomy
> University of Delaware
> 
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