On stochastic mixing caused by the Rayleigh-Taylor instability

The mixing of contacting substances is considered. The evolution of the mixing layer over a long time period from multimode initial perturbations is investigated numerically in the short-scale and wide-range cases. In the case of a short-scale initiation, the flow is stochastic in the sense that the time of the considered evolution exceeds the period of correlation. The effect of the amplitude of wide-range perturbations on the dynamics of mixing is analyzed. The scale-invariant properties of the spectral and statistical parameters of turbulent mixing are investigated for the first time. The universal spectra characterizing the turbulence mixing in the entire self-similar interval on a unified basis are obtained. The simulation is based on the effective algorithms with high approximating qualities, which have been tested earlier. (C) 2001 MAIK "Nauka/ Interperiodica".