The role of nonlinearity in turbulent diffusion models for stably stratified and rotating turbulence

Dispersion in rotating and stratified turbulence is investigated by an analytical linear model, kinematic simulations and direct numerical simulations in order to observe the impact of nonlinearity on single-particle and two-particle statistics. The anisotropy of these Lagrangian quantities is discussed in relation with the Eulerian field anisotropy and its structures, pancake- or cigar-shaped depending on the dominant body force. We show that a linear approach is valid for single-particle dispersion, and that the nonlinear structuring of the Eulerian field influences particle dispersion at long times. (C) 2006 Elsevier Inc. All rights reserved.