Nonequilibrium effects of reactive flow based on gas kinetic theory

TL;DR

This paper derives a nonequilibrium particle velocity distribution function for reactive flows using gas kinetic theory, revealing its dependence on physical quantities and derivatives, and verifies the accuracy of discrete Boltzmann models around detonation waves.

Contribution

It introduces a theoretical and numerical framework to analyze thermodynamic nonequilibrium effects in reactive flows based on gas kinetic theory.

Findings

Distribution function depends on physical quantities and derivatives, not directly on chemical reactions.

Discrete Boltzmann model accurately captures nonequilibrium distribution functions.

Kinetic moments from discrete sums closely match those from integral calculations.

Abstract

How to accurately probe chemically reactive flows with essential thermodynamic nonequilibrium effects is an open issue. Via the Chapman-Enskog analysis, the local nonequilibrium particle velocity distribution function is derived from the gas kinetic theory. It is demonstrated theoretically and numerically that the distribution function depends on the physical quantities and derivatives, and is independent of the chemical reactions directly. Based on the simulation results of the discrete Boltzmann model, the departure between equilibrium and nonequilibrium distribution functions is obtained and analyzed around the detonation wave. Besides, it has been verified for the first time that the kinetic moments calculated by summations of the discrete distribution functions are close to those calculated by integrals of their original forms.