Two-particle stochastic Eulerian-Lagrangian models of turbulent dispersion

A two-particle stochastic model of turbulent dispersion in the classical isotropic pseudoturbulence is suggested. The main idea is to describe the relative motion of two particles in small scales by a stochastic differential equation, while the dispersion in large scales is governed by the Eulerian stochastic model. This leads to the nice property of the new model: in small scales it describes properly the Richardson cubic law, and at large scales it approximates well the "two-to-one" reduction principle. (C) 1998 Published by IMACS/Elsevier Science B.V.