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Large-Scale Circulation Model for Turbulent Rayleigh-Benard Convection Eric Brown and Guenter Ahlers

Summary: Large-Scale Circulation Model for Turbulent Rayleigh-BeŽnard Convection
Eric Brown and Guenter Ahlers
Department of Physics and iQCD, University of California, Santa Barbara, California 93106, USA
(Received 8 December 2006; published 26 March 2007)
A model for the large-scale-circulation (LSC) of turbulent Rayleigh-BeŽnard convection in cylindrical
samples is presented. It consists of two physically motivated stochastic ordinary differential equations,
one each for the strength and the azimuthal orientation of the LSC. Stochastic forces represent
phenomenologically the influence of turbulent fluctuations. Consistent with measurements, the model
yields an azimuthally meandering LSC with occasional rotations, and with more rare cessations. As in
experiment, cessations have a uniform distribution of LSC orientation changes.
DOI: 10.1103/PhysRevLett.98.134501 PACS numbers: 47.27.te, 05.65.+b, 47.27.eb
Rayleigh-BeŽnard convection (RBC) consists of a fluid-
filled container heated from below [1]. Cylindrical contain-
ers with aspect ratio ÿ D=L (D is the sample diameter
and L the height) and 0:5 & ÿ & 3 have a large-scale
circulation (LSC) [2­9] that consists of warm up-flowing
and cool down-flowing fluid on opposite sides of the
sample. Its near-vertical circulation plane has an orienta-
tion 0 that undergoes azimuthal diffusion [10­12]. An
interesting aspect is that 0, in addition to its diffusive


Source: Ahlers, Guenter - Department of Physics, University of California at Santa Barbara


Collections: Physics