[mesa-users] Understanding mix_info

[Ehsan Moravveji]

Hello all,
I am trying to better understand how the boundaries of different mixing zones are set by spying into /star/private/mix_info.f. The subroutine set_mlt_boundary_info() starts from the surface and walks inward looking for the zones where there is a transition in mixing type:

         do k = 2, nz
            mt1 = s% mixing_type(k-1)
            mt2 = s% mixing_type(k)
            if (mt1 == mt2) cycle

However, there is suddenly a swap of the definition of the inner and outer layers if the outer has higher-valued mixing type:

            if (mt1 > mt2) then
               mt = mt1; mt1 = mt2; mt2 = mt
            end if

What I understand is that in such cases, then we are "locally" looking from inside towards outside.
If this is the true, please help me understand why, and if I am wrong, clarify why we need such.

Thanks for your attention
Best regards,

Ehsan