Discrete Boltzmann modeling of Rayleigh-Taylor instability in bi-component compressible flows

摘要

A discrete Boltzmann model is proposed to probe Rayleigh-Taylor (RT)instability in bi-component compressible flows. Two coupled discrete Boltzmannequations are adopted for the two species, whose specific heat ratios areadjustable. Discrete velocity models are different in the two discreteBoltzmann equations. Two types of the force term are exploited to account forgravitational effects. Apart from the recovery of a modified Navier-Stokesmodel describing fluid flows, the DBM has the capability of capturing detailednonequilibrium manifestations, which can be expressed by invariants of tensors.The global effects of the "fluctuation of translational energies" and"non-organized energy flux", and the growth rate of the entropy of mixing areinvestigated in the evolution of RT instability. It is interesting to find thatthey show decreasing, increasing, and then decreasing trends for low Reynoldsnumbers. While the early reducing tendency is particularly suppressed and eveneliminated for high Reynolds numbers. The competitive effects on nonequilibriummanifestations and mixing entropy are analysed in the process.