Extreme events for two-particles separations in turbulent flows

Abstract

Results from high resolution numerical simulations of tracer particles emitted from localised sources in homogeneous and isotropic flows are presented. A huge number of tracers are emitted in order to reach an unprecedented statistics concerning particles pairs motion. We show that the far tails of the particles pair separation Probability Distribution Function can not be described by a Richardsonlike distribution, even if finite Reynolds effects are introduced. We argue that to describe extreme event statistics, velocity temporal correlations and non-Gaussian fluctuations must be taken into account.