Thermo-hydrodynamic non-equilibrium effects on compressible Rayleigh-Taylor instability

TL;DR

This study investigates how compressibility influences Rayleigh-Taylor instability by analyzing thermodynamic and hydrodynamic non-equilibrium effects using a discrete Boltzmann model, revealing stage-dependent behaviors.

Contribution

It introduces two approaches to track TNE effects and mean temperature evolution, providing new insights into compressibility's role in RTI dynamics.

Findings

Compressibility delays initial RTI stage.

Compressibility accelerates later RTI stage.

TNE effects are enhanced by compressibility, especially later.

Abstract

The effects of compressibility on Rayleigh-Taylor instability (RTI) are investigated by inspecting the interplay between thermodynamic and hydrodynamic non-equilibrium phenomena (TNE, HNE, respectively) via a discrete Boltzmann model (DBM). Two effective approaches are presented, one tracking the evolution of the \emph{local} TNE effects and the other focussing on the evolution of the mean temperature of the fluid, to track the complex interfaces separating the bubble and the spike regions of the flow. It is found that, both the compressibility effects and the \emph{global} TNE intensity show opposite trends in the initial and the later stages of the RTI. Compressibility delays the initial stage of RTI and accelerates the later stage. Meanwhile, the TNE characteristics are generally enhanced by the compressibility, especially in the later stage. The global or mean thermodynamic non-equilibrium indicators provide physical criteria to discriminate between the two stages of the RTI.