## Abstract

We report an experimental investigation of pair dispersions in turbulent thermal convection with initial separation r_{0} ranging from sub-Kolmogorov scale to scales in the inertial range. In the dissipative range of scales we observed the exponential growth of the separation between a pair of particles predicted by Batchelor and obtained a Batchelor constant 0.23±0.07. For large r_{0}, it is found that, for almost all time ranges, both the mean-square separation and distance neighbor function exhibit the forms predicted by Batchelor, whereas the two quantities agree with Richardson's predictions for small r_{0}. Moreover, the measured value of the Richardson constant g=0.10±0.07, which is smaller than those found in other turbulence systems. We also demonstrate the crossover of the mean-square separation from the exponential to the Batchelor regimes in both temporal and spatial scales.

Original language | English (US) |
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Article number | 063006 |

Journal | Physical Review E - Statistical, Nonlinear, and Soft Matter Physics |

Volume | 87 |

Issue number | 6 |

DOIs | |

State | Published - Jun 12 2013 |

## All Science Journal Classification (ASJC) codes

- Statistical and Nonlinear Physics
- Statistics and Probability
- Condensed Matter Physics