Logarithmic Mean Temperature Profiles and Their Connection to Plume Emissions in Turbulent Rayleigh-Bénard Convection

Abstract

Two-dimensional simulations of Rayleigh-Bénard convection at Ra=5×10^10 show that vertical logarithmic mean temperature profiles can be observed in regions of the boundary layer where thermal plumes are emitted. The profile is logarithmic only in these regions and not in the rest of the boundary layer where it is sheared by the large-scale wind and impacted by plumes. In addition, the logarithmic behavior is not visible in the horizontal average. The findings reveal that the temperature profiles are strongly connected to thermal plume emission, and they support a perception that parts of the boundary layer can be turbulent while others are not. The transition to the ultimate regime, in which the boundary layers are considered to be fully turbulent, can therefore be understood as a gradual increase in the fraction of the plume-emitting (“turbulent”) regions of the boundary layer

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Citation

Copyright 2015 Physical Review Letters. Recommended citation:van der Poel, Erwin P., Rodolfo Ostilla-Mónico, Roberto Verzicco, Siegfried Grossmann, and Detlef Lohse. "Logarithmic mean temperature profiles and their connection to plume emissions in turbulent Rayleigh-Bénard convection." Physical review letters 115, no. 15 (2015): 154501. doi: 10.1103/PhysRevLett.115.154501.URL: https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.115.154501. Reproduced in accordance with the original publisher's licensing terms and with permissions from the authors.