### Abstract

Original language | Undefined |
---|---|

Pages (from-to) | 095105-1-095105-15 |

Number of pages | 15 |

Journal | Physics of fluids |

Volume | 18 |

Issue number | 9 |

DOIs | |

Publication status | Published - 2006 |

### Keywords

- METIS-233270
- IR-58108

### Cite this

*Physics of fluids*,

*18*(9), 095105-1-095105-15. https://doi.org/10.1063/1.2353400

}

*Physics of fluids*, vol. 18, no. 9, pp. 095105-1-095105-15. https://doi.org/10.1063/1.2353400

**Oscillations of the large scale wind in turbulent thermal convection.** / Resagk, Christian; du Puits, Ronald; Thess, Andre; Dolzhansky, Felix V.; Grossmann, Siegfried; Fontenele Araujo Junior, F.; Lohse, Detlef.

Research output: Contribution to journal › Article › Academic › peer-review

TY - JOUR

T1 - Oscillations of the large scale wind in turbulent thermal convection

AU - Resagk, Christian

AU - du Puits, Ronald

AU - Thess, Andre

AU - Dolzhansky, Felix V.

AU - Grossmann, Siegfried

AU - Fontenele Araujo Junior, F.

AU - Lohse, Detlef

PY - 2006

Y1 - 2006

N2 - The large scale "wind of turbulence" of thermally driven flow is analyzed for very large Rayleigh numbers between 4·1011 and 7·1011 and Prandtl number of 0.71 (air at 40 °C) and aspect ratios order of one. The wind direction near the upper plate is found to horizontally oscillate with a typical time scale very similar to the large eddy turnover time. The temporal autocorrelation of the wind direction reveals an extremely long memory of the system for the direction. We then apply and extend the dynamical model of Gledzer, Dolzhansky, and Obukhov to the flow, which is based on the Boussinesq equations in the bulk and which can be solved analytically in the inviscid and unforced limit, but which completely ignores the boundary layer and plume dynamics. Nevertheless, the model correctly reproduces both the oscillations of the horizontal wind direction and its very long memory. It is therefore concluded that the boundary layers and the plumes are not necessary to account for the oscillations of the wind direction. The oscillations rather occur as intrinsic precession of the bulk flow.

AB - The large scale "wind of turbulence" of thermally driven flow is analyzed for very large Rayleigh numbers between 4·1011 and 7·1011 and Prandtl number of 0.71 (air at 40 °C) and aspect ratios order of one. The wind direction near the upper plate is found to horizontally oscillate with a typical time scale very similar to the large eddy turnover time. The temporal autocorrelation of the wind direction reveals an extremely long memory of the system for the direction. We then apply and extend the dynamical model of Gledzer, Dolzhansky, and Obukhov to the flow, which is based on the Boussinesq equations in the bulk and which can be solved analytically in the inviscid and unforced limit, but which completely ignores the boundary layer and plume dynamics. Nevertheless, the model correctly reproduces both the oscillations of the horizontal wind direction and its very long memory. It is therefore concluded that the boundary layers and the plumes are not necessary to account for the oscillations of the wind direction. The oscillations rather occur as intrinsic precession of the bulk flow.

KW - METIS-233270

KW - IR-58108

U2 - 10.1063/1.2353400

DO - 10.1063/1.2353400

M3 - Article

VL - 18

SP - 095105-1-095105-15

JO - Physics of Fluids

JF - Physics of Fluids

SN - 1070-6631

IS - 9

ER -