A Subgrid-scale Model for Deflagration-to-Detonation Transitions in Type Ia Supernova Explosion Simulations - Numerical implementation

TL;DR

This paper introduces a subgrid-scale model for deflagration-to-detonation transitions in Type Ia supernova simulations, enabling more accurate modeling of explosion mechanisms without resolution dependence.

Contribution

The authors develop and implement a physically constrained SGS model for DDT in supernova simulations, addressing unresolved transition regions in multi-dimensional models.

Findings

Model successfully predicts DDT occurrence based on turbulence and flame surface area.

Implementation enhances the realism of supernova explosion simulations.

Model avoids resolution-dependent parameters in DDT prediction.

Abstract

A promising model for normal Type Ia supernova (SN Ia) explosions are delayed detonations of Chandrasekhar-mass white dwarfs, in which the burning starts out as a subsonic deflagration and turns at a later phase of the explosion into a supersonic detonation. The mechanism of the underlying deflagration-to-detonation transition (DDT) is unknown in detail, but necessary conditions have been determined recently. The region of detonation initiation cannot be spatially resolved in multi-dimensional full-star simulations of the explosion. We develop a subgrid-scale (SGS) model for DDTs in thermonuclear supernova simulations that is consistent with the currently known constraints. The probability for a DDT to occur is calculated from the distribution of turbulent velocities measured on the grid scale in the vicinity of the flame and the fractal flame surface area that satisfies further physical constraints, such as fuel fraction and fuel density. The implementation of our DDT criterion provides a solid basis for simulations of thermonuclear supernova explosions in the delayed detonation scenario. It accounts for the currently known necessary conditions for the transition and avoids the inclusion of resolution-dependent quantities in the model. The functionality of our DDT criterion is demonstrated on the example of one three-dimensional thermonuclear supernova explosion simulation.