Abstract
The phenomenon of irregular cessation and subsequent reversal of the large-scale circulation in turbulent Rayleigh-Bénard convection is theoretically analyzed. The force and thermal balance on a single plume detached from the thermal boundary layer yields a set of coupled nonlinear equations, whose dynamics is related to the Lorenz equations. For Prandtl and Rayleigh numbers in the range and , the model has the following features: (i) chaotic reversals may be exhibited at ; (ii) the Reynolds number based on the root mean square velocity scales as (depending on Pr), and as (depending on Ra); and (iii) the mean reversal frequency follows an effective scaling law . The phase diagram of the model is sketched, and the observed transitions are discussed.
- Received 13 July 2004
DOI:https://doi.org/10.1103/PhysRevLett.95.084502
©2005 American Physical Society