title: Onset of coherent oscillations in turbulent Rayleigh-Bénard convection.
abstract: We report temperature cross correlation and velocity profile measurements in the aspect-ratio-one convection cell filled with water. A sharp transition from a random chaotic state to a correlated turbulent state of finite coherence time is found when the Rayleigh number becomes larger than a critical value Ra(c) approximately equal to 5 x 10(7). The experiment reveals a unique mechanism for the onset of coherent oscillations in turbulent Rayleigh-Bénard convection.
authors.affiliation: Department of Physics, Oklahoma State University, Stillwater, Oklahoma 74078, USA.
authors.forename: X L
authors.initials: XL
authors.lastname: Qiu
authors.forename: P
authors.initials: P
authors.lastname: Tong