TYPE Ia SUPERNOVAE: CALCULATIONS OF TURBULENT FLAMES USING THE LINEAR EDDY MODEL

Journal Article · Sat Oct 10 00:00:00 EDT 2009 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/704/1/255· OSTI ID:21367447

Woosley, S E ^[1]; Kerstein, A R; Sankaran, V ^[2]; Aspden, A J ^[3]

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1. Department of Astronomy and Astrophysics, University of California, Santa Cruz, CA 95064 (United States)
2. Combustion Research Facility, Sandia National Laboratory, Livermore, CA 94551 (United States)
3. Center for Computational Science and Engineering, Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States)

The nature of carbon burning flames in Type Ia supernovae is explored as they interact with Kolmogorov turbulence. One-dimensional calculations using the Linear Eddy Model of Kerstein elucidate three regimes of turbulent burning. In the simplest case, large-scale turbulence folds and deforms thin laminar flamelets to produce a flame brush with a total burning rate given approximately by the speed of turbulent fluctuations on the integral scale, U{sub L} , This is the regime where the supernova explosion begins and where most of its pre-detonation burning occurs. As the density declines, turbulence starts to tear the individual flamelets, making broader structures that move faster. For a brief time, these turbulent flamelets are still narrow compared to their spacing and the concept of a flame brush moving with an overall speed of U{sub L} remains valid. However, the typical width of the individual flamelets, which is given by the condition that their turnover time equals their burning time, continues to increase as the density declines. Eventually, mixed regions almost as large as the integral scale itself are transiently formed. At that point, a transition to detonation can occur. The conditions for such a transition are explored numerically and it is estimated that the transition will occur for densities near 1 x 10{sup 7} g cm{sup -3}, provided the turbulent speed on the integral scale exceeds about 20% sonic. An example calculation shows the details of a detonation actually developing.

• OSTI ID: 21367447
• Journal Information: Astrophysical Journal, Vol. 704, Issue 1; Other Information: DOI: 10.1088/0004-637X/704/1/255; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTROPHYSICS
COSMOLOGY AND ASTRONOMY
CARBON BURNING
EXPLOSIONS
FLAMES
HYDRODYNAMICS
INTEGRALS
ONE-DIMENSIONAL CALCULATIONS
SHOCK WAVES
SUPERNOVAE
TURBULENCE
VELOCITY
BINARY STARS
ERUPTIVE VARIABLE STARS
FLUID MECHANICS
MECHANICS
STAR BURNING
STARS
VARIABLE STARS