Viscosity, heat conductivity and Prandtl number effects in Rayleigh-Taylor Instability

TL;DR

This study uses a discrete Boltzmann model to analyze how viscosity, heat conductivity, and Prandtl number influence Rayleigh-Taylor instability, revealing their effects on flow reacceleration and non-equilibrium behaviors.

Contribution

It systematically investigates the effects of viscosity, heat conductivity, and Prandtl number on Rayleigh-Taylor instability from both macroscopic and non-equilibrium perspectives, using a discrete Boltzmann approach.

Findings

Viscosity and heat conduction inhibit reacceleration by suppressing Kelvin-Helmholtz instability.

Prandtl number effect is not sensitive before reacceleration.

Non-equilibrium analysis reveals correlations between flow non-uniformity and non-equilibrium strength.

Abstract

Two-dimensional Rayleigh-Taylor(RT) instability problem is simulated with a multiple-relaxation-time discrete Boltzmann model with gravity term. The viscosity, heat conductivity and Prandtl number effects are probed from the macroscopic and the non-equilibrium views. In macro sense, both viscosity and heat conduction show significant inhibitory effect in the reacceleration stage, and the inhibition effect is mainly achieved by inhibiting the development of Kelvin-Helmholtz instability. Before this, the Prandtl number effect is not sensitive. Based on the view of non-equilibrium, the viscosity, heat conductivity, and Prandtl number effects on non-equilibrium manifestations, and the correlation degrees between the non-uniformity and the non-equilibrium strength in the complex flow are systematic investigated.