Turbulence near Onset of Convection

Abstract

New long-term (days) measurements of the evolution of turbulence for a Rayleigh-B\'enard system with aspect ratio $\ensuremath{\Gamma}=4.72$ reveal a turbulent state, with a threshold near the critical Rayleigh number ${R}_{c}$, which consists of a random background time dependence and rare, randomly spaced, major events. These events are discussed in terms of the analog of a particle under the influence of a stochastic driving force and in a potential with two minima.