题 目：How Tabletop Turbulence Experiments Can Help Understand Large-scale Fluid Phenomena in Nature?
The phenomenon of thermal convection occurs widely in nature, such as atmospheric and oceanic circulations; convection in the Earth mantel and its outer core; and in the Sun. A paradigm for the study of turbulent thermal convection is the Rayleigh-Bénard system. After a brief introduction of the system and review of some recent results, I will show how the Rayleigh-Bénard convection can be used as a platform for studying some large-scale fluid problems in nature. Specifically, I will present results from our recent Lagrangian particle tracking experiments in turbulent thermal convection. I will show what can be learned from particle tracking experiments in thermal turbulence and its implications for the dispersion and mixing of scalars by turbulent flows in which buoyancy plays an important role. A few examples will be presented, which include particle pair dispersion with small initial separations, acceleration statistics, and local energy dissipation rate.