Experimental Analysis of Chaotic Transport and Lagrangian Coherent Structures in Rayleigh-Benard Convection

Abstract

When the Rayleigh number Ra is set at a number slightly larger than a critical number Rat, the velocity field of Rayleigh-Benard convection is to be perturbed. Such convection has been modeled as a two-dimensional Hamiltonian model with perturbations, in which chaotic transport is induced by the entanglement of invariant manifolds. However, invariant manifolds of Rayleigh-Benard convection has not been enough investigated in experiments. In this research, we measure the two-dimensional velocity field of Rayleigh-Benard convection by particle image velocimetry (PIV), detect such invariant manifolds as Lagrangian coherent structures (LCSs) in experiments, and finally show that fluid particles are transported chaotically in perturbed Rayleigh-Benard convection as in the Hamiltonian model.