Experimental investigation of pair dispersion with small initial separation in convective turbulent flows

Abstract

We report an experimental investigation of pair dispersions in turbulent thermal convection with initial separation r0 ranging from sub-Kolmogorov scale to scales in the inertial range. In the dissipative range of scales we observed for the first time in experiment the exponential growth of the separation between a pair of particles predicted by Batchelor and obtained a Batchelor constant 0.23\pm0.07. For large r0, it is found that, for almost all time range, 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 r0. Moreover, the measured value of the Richardson constant g = 0.10 \pm 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.

5 pages, 4 figures

References in corpus (4)

• Large scale dynamics in turbulent Rayleigh-Benard convection
• Lagrangian studies in convective turbulence
• Lagrangian dispersion and heat transport in convective turbulence
• On the Kolmogorov Constants for the Second-Order Structure Function and the Energy Spectrum

Cited by in corpus (6)

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• On the role of initial velocities in pair dispersion in a microfluidic chaotic flow
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• Do fluid particles separate exponentially in the dissipation range?
• Objective quantification of Particle Pair Diffusion in Homogeneous Isotropic Turbulence