Numerical Study of Two Fluid Rayleigh-Taylor Instability

A new computing technique for the time-dependent calculation of the interaction of two incompressible fluids is used to study the linear and nonlinear phases of Rayleigh-Taylor instability. The variation of the linear growth rate with Reynolds number is examined for Reynolds numbers 200 at a ratio of fluid densities of 2 : 1. These findings support Chandrasekhar's predictions of the magnitude of the growth rate and the Reynolds number for which maximum growth rate is attained. A series of inviscid flow calculations, at density ratios between 1.1 : 1 and 10 : 1, is used to explore the effect of density ratio on aspects of the nonlinear Rayleigh-Taylor instability. It is found that such influences as form drag and Kelvin-Helmholtz instability decrease rapidly in importance as the density ratio increases.