[mesa-users] derivative for mlt, semiconvection, overshoot

[David Arnett]

These algorithms are for the steady state limit, so they become unphysical
for small time steps. What is worse, they do not have careful treatments of
boundaries, where more problems happen. These issues are swept under the
rug by using a diffusion operator for convective mixing. It is becoming
clear that the problem of boundaries is related to narrow turbulent
boundary layers, and the problem of time steps is related to the dynamics
of integral scale flows in the convection zone. Until we solve this we are
stuck with what we now have, and should be skeptical about our results
regarding both small time scales and boundaries.

-- 
David Arnett
Regents Professor
Steward Observatory
University of Arizona

Facts are stubborn, but statistics are more pliable.  Mark Twain
Facts do not cease to exist because they are ignored.  Aldous Huxley
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