Development of the Rayleigh-Taylor Instability. Results of Numerical Simulation at Low Reynolds Numbers

The development of the Rayleigh-Taylor instability is studied by solving numerically two-dimensional Navier-Stokes equations for a viscous compressible gas in a uniform field of an external body force. The main attention is paid to the change in the flow pattern with an increase in the Knudsen number (and, accordingly, a decrease in the inversely proportional Reynolds number) and the increasing influence of the effects of viscosity and flow rarefaction. It is determined at what value of the Knudsen number the development of secondary Kelvin-Helmholtz instability is suppressed. Usually the Kelvin-Helmholtz instability plays the main role in the emergence of small-scale pulsations and the transition to turbulence. The dependence of the growth rate of the spike formed by the heavier gas on the flow rarefaction is studied.