Transport of a passive scalar and Lagrangian chaos in a Hamiltonian hydrodynamic system

An experimental and numerical study is made of the chaotic behavior of Lagr angian trajectories and transport of a passive tracer in a quasi-two-dimens ional four-vortex flow with a periodic time dependence of the Euler velocit y field. Quantitative measurements are made of tracer transport between iso lated vortices in physical space and in "action" variable space. The theory of adiabatic chaos is used to interpret the measurements. The simplest phe nomenological models of liquid particle random walks are proposed to descri be the anomalous transport in terms of the action. (C) 2000 MAIK "Nauka/Int erperiodica".