📝 SummarXiv

Abstract

We present an information-theoretic characterization of small-scale intermittency in turbulent flows, that distinguishes turbulence-induced intermittency from purely kinematic effects. Kullback-Leibler (KL) divergence is used to quantify the deviation of pseudodissipation, dissipation or enstrophy of a turbulent flow field from that of a Gaussian random velocity field, serving as a comprehensive measure of the small-scale intermittency arising from turbulence dynamics. Shannon entropy is employed to evaluate the uncertainty of these small-scale quantities. Analysis of direct numerical simulation data of forced homogeneous isotropic turbulent flow across a wide range of Taylor Reynolds numbers demonstrates the existence of two critical Reynolds numbers where the variation of uncertainty changes. The study reveals a new scaling behavior and presence of a symmetry: (i) turbulence-induced intermittency grows logarithmically with Reynolds number unlike the commonly reported power-law scaling and (ii) turbulence dynamics produce equal intermittency in both dissipation rate and enstrophy, in contrast to the prevailing assumptions of asymmetry in strain-rate and vorticity dynamics.