### Abstract

We present experimental evidence that, in the hard turbulence regime of Rayleigh-Bénard convection, the temperature fluctuations are produced by buoyancy, despite the presence of a mean horizontal flow at the plates. In a convection cell of aspect ratio 1, we measure the temperature time derivative for Ra from 2×[Formula Presented] to 1×[Formula Presented], which is skewed toward the negative in the region outside the cold thermal boundary layer. This skewness of the derivative indicates the presence of thermal fronts, or plumes, which are detached from the boundary layer by buoyancy. At higher Ra, the skewness of the derivative is reduced, which we relate to the transition to a turbulent Reynolds number in the velocity boundary layer at Ra∼[Formula Presented]. We define a time scale using the derivative to characterize these fronts, and find that its minimum value scales as [Formula Presented] over the entire range of Ra in our experiment.

Original language | English (US) |
---|---|

Pages (from-to) | 4893-4898 |

Number of pages | 6 |

Journal | Physical Review E - Statistical Physics, Plasmas, Fluids, and Related Interdisciplinary Topics |

Volume | 53 |

Issue number | 5 |

DOIs | |

State | Published - Jan 1 1996 |

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### All Science Journal Classification (ASJC) codes

- Statistical and Nonlinear Physics
- Mathematical Physics
- Condensed Matter Physics
- Physics and Astronomy(all)

### Cite this

}

*Physical Review E - Statistical Physics, Plasmas, Fluids, and Related Interdisciplinary Topics*, vol. 53, no. 5, pp. 4893-4898. https://doi.org/10.1103/PhysRevE.53.4893

**Thermal signature of plumes in turbulent convection : The skewness of the derivative.** / Belmonte, Andrew; Libchaber, Albert.

Research output: Contribution to journal › Article

TY - JOUR

T1 - Thermal signature of plumes in turbulent convection

T2 - The skewness of the derivative

AU - Belmonte, Andrew

AU - Libchaber, Albert

PY - 1996/1/1

Y1 - 1996/1/1

N2 - We present experimental evidence that, in the hard turbulence regime of Rayleigh-Bénard convection, the temperature fluctuations are produced by buoyancy, despite the presence of a mean horizontal flow at the plates. In a convection cell of aspect ratio 1, we measure the temperature time derivative for Ra from 2×[Formula Presented] to 1×[Formula Presented], which is skewed toward the negative in the region outside the cold thermal boundary layer. This skewness of the derivative indicates the presence of thermal fronts, or plumes, which are detached from the boundary layer by buoyancy. At higher Ra, the skewness of the derivative is reduced, which we relate to the transition to a turbulent Reynolds number in the velocity boundary layer at Ra∼[Formula Presented]. We define a time scale using the derivative to characterize these fronts, and find that its minimum value scales as [Formula Presented] over the entire range of Ra in our experiment.

AB - We present experimental evidence that, in the hard turbulence regime of Rayleigh-Bénard convection, the temperature fluctuations are produced by buoyancy, despite the presence of a mean horizontal flow at the plates. In a convection cell of aspect ratio 1, we measure the temperature time derivative for Ra from 2×[Formula Presented] to 1×[Formula Presented], which is skewed toward the negative in the region outside the cold thermal boundary layer. This skewness of the derivative indicates the presence of thermal fronts, or plumes, which are detached from the boundary layer by buoyancy. At higher Ra, the skewness of the derivative is reduced, which we relate to the transition to a turbulent Reynolds number in the velocity boundary layer at Ra∼[Formula Presented]. We define a time scale using the derivative to characterize these fronts, and find that its minimum value scales as [Formula Presented] over the entire range of Ra in our experiment.

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U2 - 10.1103/PhysRevE.53.4893

DO - 10.1103/PhysRevE.53.4893

M3 - Article

AN - SCOPUS:0000471554

VL - 53

SP - 4893

EP - 4898

JO - Physical Review E

JF - Physical Review E

SN - 2470-0045

IS - 5

ER -