Determine whether thermohaline mixing has problems at highT

[rjfarmer]

This is a problem i see often with models going to core collapse. Models with thermohaline mixing on, around oxygen ignition, grind to a halt. What seems to happen is we have some thermohaline mixing at the very center, the oxygen ignites slightly off center above the mixing. This thermohaline blob then stops the burning from moving inwards to the center and the model then proceeds with tiny time steps.

The solution is usually just turn off thermohaline mixing at late times and as its a slow process its probably not got enough time to actually do anything to the model, but then that also begs the question why its having any effect on core burning in the first place.

I'm leaving this bug here in case any one else runs in this, or is motivated to work out why and whether we need to fix something about the mixing/burning.

[fxt44]

i've seen this many times in the past. these days, as a result, i simply turn thermohaline off.

[adamjermyn]

What’s the time-scale from oxygen ignition to collapse versus the thermohaline mixing scale (e.g. r^2 / D_mix)? That would be useful to know for thinking about this...

-Adam On May 18, 2020, 5:22 AM -0400, Robert Farmer [email protected], wrote:

This is a problem i see often with models going to core collapse. Models with thermohaline mixing on, around oxygen ignition, grind to a halt. What seems to happen is we have some thermohaline mixing at the very center, the oxygen ignites slightly off center above the mixing. This thermohaline blob then stops the burning from moving inwards to the center and the model then proceeds with tiny time steps. The solution is usually just turn off thermohaline mixing at late times and as its a slow process its probably not got enough time to actually do anything to the model, but then also begs the question why its having any effect on the core burning in the first place. I'm leaving this bug here in case any one else runs in this, or is motivated to work out why and whether we need to fix something about the mixing/burning. — You are receiving this because you are subscribed to this thread. Reply to this email directly, view it on GitHub, or unsubscribe.