Three-dimensional numerical simulations of Rayleigh-Taylorunstable flames in type Ia supernovae

Journal Article · Fri Jan 28 04:00:00 EST 2005 · Astrophysical Journal

OSTI ID:862068

Zingale, M; Woosley, S E; Rendleman, C A; Day, M S; Bell, J B

Flame instabilities play a dominant role in accelerating the burning front to a large fraction of the speed of sound in a Type Ia supernova. We present a three-dimensional numerical simulation of a Rayleigh-Taylor unstable carbon flame, following its evolution through the transition to turbulence. A low Mach number hydrodynamics method is used, freeing us from the harsh time step restrictions imposed by sound waves. We fully resolve the thermal structure of the flame and its reaction zone, eliminating the need for a flame model. A single density is considered, 1.5x107 gm/cc, and half carbon/half oxygen fuel--conditions under which the flame propagated in the flamelet regime in our related two-dimensional study. We compare to a corresponding two-dimensional simulation, and show that while fire-polishing keeps the small features suppressed in two dimensions, turbulence wrinkles the flame on far smaller scales in the three-dimensional case, suggesting that the transition to the distributed burning regime occurs at higher densities in three dimensions. Detailed turbulence diagnostics are provided. We show that the turbulence follows a Kolmogorov spectrum and is highly anisotropic on the large scales, with a much larger integral scale in the direction of gravity. Furthermore, we demonstrate that it becomes more isotropic as it cascades down to small scales. Based on the turbulent statistics and the flame properties of our simulation, we compute the Gibson scale. We show the progress of the turbulent flame through a classic combustion regime diagram, indicating that the flame just enters the distributed burning regime near the end of our simulation.

• Research Organization: Ernest Orlando Lawrence Berkeley NationalLaboratory, Berkeley, CA (US)
• Sponsoring Organization: USDOE Director. Office of Science. Office of AdvancedScientific Computing Research. Mathematical Information and ComputationalSciences Division, Supernoval Science Center DE-FC02-01ER41176; NationalAeronautics and Space Administration NAG5-12036
• DOE Contract Number: AC02-05CH11231
• OSTI ID: 862068
• Report Number(s): LBNL--56966
• Journal Information: Astrophysical Journal, Journal Name: Astrophysical Journal Journal Issue: 2pt1 Vol. 632; ISSN ASJOAB; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
CARBON
COMBUSTION
DIMENSIONS
FLAMES
HYDRODYNAMICS
MACH NUMBER
OXYGEN
SIMULATION
SOUND WAVES
STATISTICS
SUPERNOVAE
TURBULENCE
VELOCITY
supernovae white dwarfs hydrodynamics numericalmethods