The deflagration mode of flame propagation in Type Ia supernova (SN Ia) models requires a correct description of the interaction of the flame with turbulent motions. It is well-known that turbulent combustion proceeds in different regimes. For most parts of the deflagration in SNe Ia the flamelet regime applies. This has been modeled in previous multi-dimensional simulations. However, at late s...

Turbulent combustion is three-dimensional. Turbulence in a Type Ia supernova is driven on large scales by the buoyancy of burning products. The turbulent cascade penetrates down to very small scales, and makes the rate of deflagration independent of the microphysics. The competition between the turbulent cascade and the freeze-out of turbulent motions due to stellar expansion determines the lar...

Large-scale, three-dimensional numerical simulations of the deflagration stage of a thermonuclear supernova explosion show the formation and evolution of a highly convoluted turbulent flame in the gravitational field of an expanding carbon-oxygen white dwarf. The flame dynamics are dominated by the gravity-induced Rayleigh-Taylor instability that controls the burning rate. The thermonuclear def...

Aims. We present the first full-star three-dimensional explosion simulations of thermonuclear supernovae including parameterized deflagration-to-detonation transitions that occur once the flame enters the distributed burning regime. Methods. Treating the propagation of both the deflagration and the detonation waves in a common front-tracking approach, the detonation is prevented from crossing a...

The Deflagration to Detonation Transition (DDT) in large arrays (100s) of explosive devices is investigated using large-scale computer simulations running the Uintah Computational Framework. Our particular interest is understanding the fundamental physical mechanisms by which convective deflagration of cylindrical PBX 9501 devices can transition to a fully-developed detonation in transportation...

We present a new mechanism for Type Ia supernova explosions in massive white dwarfs. The proposed scenario follows from relaxing the assumption of symmetry in the model and involves a detonation created in an unconfined environment. The explosion begins with an essentially central ignition of stellar material initiating a deflagration. This deflagration results in the formation of a buoyantly-d...

The energy released in a magnetic material by reversing spins as they relax toward equilibrium can lead to a dynamical instability that ignites self-sustained rapid relaxation along a deflagration front that propagates at a constant subsonic speed. Using a trigger heat pulse and transverse and longitudinal magnetic fields, we investigate and control the crossover between thermally driven magnet...

The study on deflagration-to-detonation transition (DDT) is very important because this mechanism has relevance to safety issues in industries, where combustible premixed gases are in general use. However, the quantitative prediction of DDT is one of the major unsolved problems in combustion and detonation theory to date. In this paper, the DDT process is studied theoretically and the critical ...

The flame born in the deep interior of a white dwarf that becomes a Type Ia supernova is subject to several instabilities, the combination of which determines the observational characteristics of the explosion. We briefly review these instabilities and discuss the length scales for which each dominates. Their cumulative effect is to accelerate the speed of the flame beyond its laminar value, bu...