Light particles in turbulence: velocity statistics

ORAL

Abstract

We conduct experiments to study light particles in turbulence using Particle Tracking Velocimetry (PTV) in three-dimensions. Microbubbles are dispersed in a homogenous and isotropic turbulent flow in the Twente water tunnel. The size of the microbubbles is fixed and is comparable to the Kolmogorov length scale of the flow. The Lagrangian velocity statistics of the microbubbles are obtained from the trajectories captured using PTV. The velocity statistics (PDF, autocorrelation and structure functions) of microbubbles are studied at different $Re$ and compared with previous experiments and numerics for particles in turbulence. The velocity PDF of the 3 velocity components (x, y and z) show a robust gaussian profile (independent of Re) with flatness values between 2.74 to 3.25. We calculate the velocity autocorrelation and find that the decorrelation time increases with increasing $Re$. We also calculate the second and fourth - order velocity structure functions and find a reasonable agreement with previous numerical simulations.

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Authors

  • Vivek Nagendra Prakash

    Physics of Fluids Group, University of Twente

  • Julian Martinez Mercado

    Physics of Fluids Group, University of Twente

  • Yoshiyuki Tagawa

    The University of Twente, University of Twente, The Netherlands, Physics of Fluids Group, University of Twente

  • Chao Sun

    The University of Twente, University of Twente, Physics of Fluids group, University of Twente, University of Twente, The Netherlands, Physics of Fluids Group, University of Twente

  • Detlef Lohse

    The University of Twente, University of Twente, Physics of Fluids group, University of Twente, Physics of Fluids, Twente University, The Netherlands, University of Twente, The Netherlands, Physics of Fluids, University of Twente, Physics of Fluids Group, University of Twente