Lagrangian statistics of light particles in turbulence

J. Martinez Mercado, Vivek Nagendra Prakash, Y. Tagawa, Chao Sun, Detlef Lohse

Research output: Contribution to journalArticleAcademicpeer-review

24 Citations (Scopus)

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 db = 340 ¿m 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. 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 to 30. The acceleration flatness values show an increasing trend with Re¿, consistent with previous experiments [G. Voth, A. La Porta, A. M. Crawford, J. Alexander, and E. Bodenschatz, ¿Measurement of particle accelerations in fully developed turbulence,¿ J. Fluid Mech. 469, 121 (2002)]10.1017/S0022112002001842 and numerics [T. Ishihara, Y. Kaneda, M. Yokokawa, K. Itakura, and A. Uno, ¿Small-scale statistics in highresolution direct numerical simulation of turbulence: Reynolds number dependence of one-point velocity gradient statistics,¿ J. Fluid Mech. 592, 335 (2007)]10.1017/S0022112007008531 . These acceleration PDFs show a higher intermittency compared to tracers [S. Ayyalasomayajula, Z. Warhaft, and L. R. Collins, ¿Modeling inertial particle acceleration statistics in isotropic turbulence,¿ Phys. Fluids. 20, 095104 (2008)]10.1063/1.2976174 and heavy particles [S. Ayyalasomayajula, A. Gylfason, L. R. Collins, E. Bodenschatz, and Z. Warhaft, ¿Lagrangian measurements of inertial particle accelerations in grid generated wind tunnel turbulence,¿ Phys. Rev. Lett. 97, 144507 (2006)]10.1103/PhysRevLett.97.144507 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 Kármán flows and point-particle direct numerical simulations with periodic boundary conditions.
Original languageEnglish
Article number055106
Pages (from-to)-
Number of pages14
JournalPhysics of fluids
Volume24
Issue number5
DOIs
Publication statusPublished - 2012

Keywords

  • METIS-288413
  • IR-81790

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