0 Three - Dimensional Modeling of the Deflagration Stage of

The paper describes a physical model and numerical algorithm for modeling Type Ia supernova (SNIa) explosions in three-dimensions and presents first results of modeling a deflagration explosion in a non-rotating, Chandrasekhar-mass carbon-oxygen (CO) white dwarf. Simulations show that the turbulent flame speed grows exponentially, reaches ≃ 30% of the speed of sound, and then declines as the large-scale turbulence is frozen by expansion. The freezing of turbulent motions appears to be a crucial physical mechanism regulating the rate of deflagration in SNIa. The energy of the explosion is comparable to that of a typical SNIa. However, the presence of the outer layer of unburned CO and the formation of intermediate mass elements and pockets of unburned CO near the center pose problems for the modeling of SNIa spectra. Delayed detonation is a way to alleviate these problems and to produce consistent spectra.