Turbulence-flame interaction on the early evolution of flames in type Ia supernovae

Type Ia supernovae are bright stellar explosions thought to occur when a runaway thermonuclear reaction incinerates a compact star known as white dwarf (WD). In many models, the explosion begins with a flame born in the turbulent environment near the center of the white dwarf. The effect of turbulence on the evolution of the nascent flame is incompletely understood and is the subject of active research. The range of length scales from the full star (∼ 10 ⁸ cm) to the laminar flame width (∼ 10 ^-5 cm) prevents full-star simulations from resolving the turbulence-flame interaction (TFI) directly. In the single-degenerate paradigm of Type Ia supernovae (SNe Ia), the WD experiences ∼ 1000 year period of convection as the temperature rises to burn carbon. When the nuclear burning timescale exceeds the turnover time for convective eddies, a flame is born in the center of a vigorous convection field (v _rms ∼ 400 km/s) extending out to enclose ∼ 70% of the WD's mass [1]. We present preliminary results from a physically-motivated TFI model inspired by Colin et al. (2000) [2] that utilizes a local, instantaneous measure of the turbulence to enhance the flame speed due to under-resolved TFI. We explore various implementation choices in the TFI model and compare results to previous work. We present two simulations of the early flame evolution in a supernova. One incorporates a TFI model with particular implementation choices, while the other relies only on indirect buoyancy effects [3].