Experimental evidence of chaotic advection in a convective flow

Lagrangian chaos is experimentally investigated in a convective flow by mea ns of Particle Tracking Velocimetry. The Finite Size Lyapunov Exponent anal ysis is applied to quantify dispersion properties at different scales. In t he range of parameters of the experiment, Lagrangian motion is found to be chaotic. Moreover, the Lyapunov exponent depends on the Rayleigh number as Ra-1/2. A simple dimensional argument for explaining the observed power law scaling is proposed.