Structure based statistical theory of intermittency

Abstract

A general statistical theory of the intermittency in turbulence based on short-lived coherent structures (instantons) is presented. The probability density functions (PDFs) of the flux R are shown to have an exponential scaling P(R)∝exp(−cRs) in the tails, with the exponent s=(n+1)∕m. Here, n and m are the order of the highest nonlinear interaction term and moments for which the PDFs are computed, respectively; c is constant depending on spatial profile of the coherent structure. The results can have important implications for understanding the universality often observed in simulations and experiments.