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arXiv · 1109.0188

Lagrangian statistics of light particles in turbulence

Julian Martinez Mercado·Vivek N. Prakash·Yoshiyuki Tagawa·Chao Sun·Detlef Lohse
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Abstract

We study the Lagrangian velocity and acceleration statistics of light particles (micro-bubbles in water) in homogeneous isotropic turbulence. Micro-bubbles with a diameter of 340 microns and Stokes number from 0.02 to 0.09 are dispersed in a turbulent water tunnel operated at Taylor-Reynolds numbers (Re) ranging from 160 to 265. We reconstruct the bubble trajectories by employing three-dimensional particle tracking velocimetry (PTV). It is found that the probability density functions (PDFs) of the micro-bubble acceleration show a highly non-Gaussian behavior with flatness values in the range 23-30. The acceleration flatness values show an increasing trend with Re, consistent with previous experiments (Voth et al., JFM, 2002) and numerics (Ishihara et al., JFM, 2007). These acceleration PDFs show a higher intermittency compared to tracers (Ayyalasomayajula et al., Phys. Fluids, 2008) and heavy particles (Ayyalasomayajula et al., Phys. Rev. Lett., 2006) in wind tunnel experiments. In addition, the micro-bubble acceleration autocorrelation function decorrelates slower with increasing Re. We also compare our results with experiments in von Karman flows and point-particle direct numerical simulations with periodic boundary conditions.

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Julian Martinez Mercado, Vivek N. Prakash, Yoshiyuki Tagawa, Chao Sun, Detlef Lohse. 2012-02-06. Lagrangian statistics of light particles in turbulence. https://doi.org/10.1063/1.4719148

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