Double-distribution-function discrete Boltzmann model for combustion

TL;DR

This paper introduces a two-species discrete Boltzmann model for combustion that captures nonequilibrium behaviors and improves detail simulation over single distribution models, applicable to subsonic and supersonic regimes.

Contribution

The paper develops a double-distribution-function discrete Boltzmann model for combustion, enhancing physical accuracy and detail simulation compared to existing single distribution models.

Findings

Model accurately simulates both subsonic and supersonic combustion.

Physical accuracy improves with higher-order moment relations.

Compared with single distribution models, it captures more combustion details.

Abstract

A 2-dimensional discrete Boltzmann model for combustion is presented. Mathematically, the model is composed of two coupled discrete Boltzmann equations for two species and a phenomenological equation for chemical reaction process. Physically, the model is equivalent to a reactive Navier-Stokes model supplemented by a coarse-grained model for the thermodynamic nonequilibrium behaviours. This model adopts 16 discrete velocities. It works for both subsonic and supersonic combustion phenomena with flexible specific heat ratio. To discuss the physical accuracy of the coarse-grained model for nonequilibrium behaviours, three other discrete velocity models are used for comparisons. Numerical results are compared with analytical solutions based on both the first-order and second-order truncations of the distribution function. It is confirmed that the physical accuracy increases with the increasing moment relations needed by nonequlibrium manifestations. Furthermore, compared with the single distribution function model, this model can simulate more details of combustion.