TURBULENCE IN A THREE-DIMENSIONAL DEFLAGRATION MODEL FOR TYPE Ia SUPERNOVAE. II. INTERMITTENCY AND THE DEFLAGRATION-TO-DETONATION TRANSITION PROBABILITY

Abstract

The delayed detonation model describes the observational properties of the majority of type Ia supernovae very well. Using numerical data from a threedimensional deflagration model for type Ia supernovae, the intermittency of the turbulent velocity field and its implications on the probability of a deflagrationto-detonation (DDT) transition are investigated. From structure functions of the

Magnetic Fields in Diffuse Media

“…Unexpectedly, the p departure from a linear dependence agrees, within the error bars, with the predictions for incompressible turbulence (She and Lévêque 1994). The multifractal geometry of the E-CVIs structures in the Polaris Flare probed by the non-linear dependence of p with p up to p D 6 discussed in is now confirmed, up to higher orders, by the analysis of this larger data set.…”

“…the smaller the scale, the larger the spatio-temporal velocity fluctuations, relative to their average value. The most successful is certainly the one proposed by She and Lévêque (1994) who infer the relation The statistical properties of the velocity fluctuations have been widely studied experimentally in laboratory and atmospheric flows: in all cases, the statistics of velocity derivative and increments signals are found to be non-Gaussian, with large departures from the average more frequent than for a Gaussian distribution.…”

“…The intermittency model of She and Lévêque (1994) was generalized by taking into account different possibilities for the co-dimension of the structures of high dissipation C and the scaling exponent of the increments in the inertial range ıu ıb / 1=g In the inertial range l D r L, they scale as S fu;bg p .r/ / r fu;bg p .…”

A subgrid-scale model for deflagration-to-detonation transitions in Type Ia supernova explosion simulations

“…The fit should further be motivated by an appropriate distribution function that can explain the intermittent behavior in turbulence at the flame. Schmidt et al (2010) used a log-normal distribution of an intermittency model of Kolmogorov (1962) and Oboukhov (1962) to fit characteristic scaling exponents that were obtained from the computation of high-order velocity correlation functions. This detailed analysis revealed that the intermittency in ash regions is weaker than predicted in the log-normal model.…”

Turbulence model for simulation of the flame front propagation in SNIa

“…The flame acceleration (the final Mach number) ∼ 0.05c s is small and we can conclude, similar to [13], that deflagration to detonation transition occurs in different regime of turbulent burning (not in the flamelet), or on the border of two regimes (there could be identified three regimes of turbulent burning -the flamelet, the stirred flame, the well-stirred flame, for additional details see [13]) of turbulent flame propagation. It is important to note that this conclusion refers to the whole flame, according to [12,34] …”