Observation of anomalous diffusion and Lévy flights in a two-dimensional rotating flow

Abstract

Chaotic transport in a laminar fluid flow in a rotating annulus is studied experimentally by tracking large numbers of tracer particles for long times. Sticking and unsticking of particles to remnants of invariant surfaces (Cantori) around vortices results in superdiffusion: The variance of the displacement grows with time as ${\mathit{t}}_{\mathrm{\delta }}$ with γ=1.65±0.15. Sticking and flight time probability distribution functions exhibit power-law decays with exponents 1.6±0.3 and 2.3±0.2, respectively. The exponents are consistent with theoretical predictions relating Lévy flights and anomalous diffusion.