On the spectral and statistical properties of Rayleigh-Taylor mixing

Dynamics of turbulent mixing due to the Rayleigh-Taylor instability is considered. The mixing layer consists of a single horizontal array of large-scale structures. The characteristics of these structures are studied by the spectral and statistical methods. Mixing stimulation by long-wavelength noise is studied. It is demonstrated that, for typical homogeneous unscaled noise, self-similarity h∝t ² is retained. The threshold amplitude of random broadband noise is determined, below which this noise can be ignored. The mixing deceleration by the side boundaries is studied. The stimulation and deceleration effects sizably influence the mixing coefficient α₊, increasing and decreasing it, respectively.