The Turbulent Diffusivity of Convective Overshoot Daniel Lecoanet Josiah Schwab, Eliot Quataert Lars Bildsten, Frank Timmes Geoff Vasil, Keaton Burns Jeff Oishi, Ben Brown Supported by: NSF, Hertz Foundation, NASA, ARC
The problem Stably stratified Convection
The problem Stably stratified Convection
The problem how much Stably stratified mix ixing? what kin ind? Convection
Super Asymptotic Giant Branch stars H MS
Super Asymptotic Giant Branch stars H He MS RGB
Super Asymptotic Giant Branch stars H He CO MS RGB AGB
Super Asymptotic Giant Branch stars H He CO MS RGB AGB
Super Asymptotic Giant Branch stars H He CO MS RGB AGB SAGB
Frank Timmes Flame Carbon Temperature Density Energy Generation Inner star Outer star
Farmer+ 2015
Does flame reach center??? Farmer+ 2015
Does flame reach center??? Yes: ONe core e - capture SNe SNe II-P Farmer+ 2015
Does flame reach center??? Yes: No: ONe core ``Hybrid’’ WD e - capture SNe SNe Ia? SNe II-P ??? Farmer+ 2015
Carbon Flames
Carbon Flames
Carbon Flames flame dies
Carbon Flames flame dies flame is fine
Carbon Flames flame dies flame is fine
Carbon Flames Properties
Carbon Flames Properties
Carbon Flames Properties
Carbon Flames Model
Carbon Flames Model negative in conv VERY positive in flame
Carbon Flames Model
Carbon Flames Model BC’s: no slip, no temperature perturbation 3D domain, 4H x 4H x 2H
Carbon Flames Model BC’s: no slip, no temperature perturbation 3D domain, 4H x 4H x 2H
Carbon Flames Properties
Carbon Flames Properties
Dedalus Pseudo-spectral Open-source Pyth ython ** Very ry fl flexible equations **
The team so far Daniel Lecoanet (Berkeley) Keaton Burns (MIT) Jeff Oishi (Bates College) Ben Brown (Colorado) Geoff Vasil (Sydney)
flame
Passive Scalar Field
Passive Scalar Field
Passive Scalar Field
Passive Scalar Field
Passive Scalar Field Ansatz:
Passive Scalar Field
Turbulent Diffusivity
Turbulent Diffusivity Solve: Does it work?
Turbulent Diffusivity Solve: Does it work? fit
Turbulent Diffusivity Solve: Turbulent diffusivity is a good approximation!
Do Carbon Flames Mix? Need deep within the flame
Conclusion 1. Penetrative convection mixes fluid like a turbulent diffusivity 2. Very little mixing in regions which are very stable 3. Convective overshoot probably can’t stall flames
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