Morphological and non-equilibrium analysis of coupled Rayleigh-Taylor-Kelvin-Helmholtz instability

Abstract

In this paper, the coupled Rayleigh-Taylor-Kelvin-Helmholtz instability (RTI, KHI, and RTKHI, respectively) system is investigated using a multiple-relaxation-time discrete Boltzmann model. Both the morphological boundary length and thermodynamic non-equilibrium (TNE) strength are introduced to probe the complex configurations and kinetic processes. In the simulations, RTI always plays a major role in the later stage, while the main mechanism in the early stage depends on the comparison of buoyancy and shear strength. It is found that both the total boundary length L of the condensed temperature field and the mean heat flux strength D3,1 can be used to measure the ratio of buoyancy to shear strength and to quantitatively judge the main mechanism in the early stage of the RTKHI system. Specifically, when KHI (RTI) dominates, LKHI > LRTI LKHI < LRTI, D3,1KHI>D3,1RTI D3,1KHI