Computing turbulent flows driven by Rayleigh-Taylor and Richtmyer-Meshkov instabilities

We develop a two-scale turbulence model for turbulent mix induced by Rayleigh-Taylor and Richtmyer-Meshkov instabilities. In this model, the large scales are dominated by production by instability mechanisms, while small scales satisfy Kolmogorov dynamics. The model allows transfer rates in the two spectral regions to be unequal. Constraints on model coefficients that permit relaxation to a unique self-similar state in free decay and self-similar growth are derived.