Turbulent erosion of a stably stratified fluid as a test of intermittency models

As a model for the erosion of a stably stratified fluid by an overlying turbulent region, the rate of advance of the mixing interface is calculated in terms of the probability distribution for eddies as a function of their size and velocity. Predicted rates of advance are then evaluated for two current models of intermittency in small-scale turbulence. Compared to available experimental data, one intermittency model, the β-model, is found to be in good agreement, while the other, the log-normal hypothesis, is discordant; unfortunately, the Reynolds number of the existing experiments is not large enough to yield a definitive test. At higher Re, similar experiments might be a useful complement to the alternative of measuring high-order moments. Some related experiments are suggested to test the model and measure the fractal dimension D.