On bubble clustering and energy spectra in pseudo-turbulence

ORAL

Abstract

We performed 3D-Particle Tracking (3D-PTV) and Phase Sensitive Constant Temperature Anemometry in pseudo-turbulence to investigate bubble clustering and to obtain the mean bubble rise velocity, distributions of bubble velocities, and energy spectra at dilute gas concentrations. To characterize the clustering the pair correlation function $G(r,\theta)$ is calculated. The deformable bubbles with equivalent bubble diameter $d_b=4-5$ mm are found to cluster within a radial distance of a few bubble radii with a preferred vertical orientation. This vertical alignment is present at both small and large scales. The large number of data-points and the non intrusiveness of PTV allowed to obtain well-converged Probability Density Functions (PDFs) of the bubble velocity. The PDFs have a non-Gaussian form for all velocity components and intermittency effects can be observed. The energy spectrum of the liquid fluctuations decays with a power law of $-3.2$, different from the $\approx -5/3$ found for homogeneous isotropic turbulence.

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Authors

  • Julian Martinez Mercado

    Physics of Fluids Group, Faculty of Science and Technology, University of Twente

  • Daniel Chehata Gomez

    Physics of Fluids Group, Faculty of Science and Technology, University of Twente

  • Dennis van Gils

    University of Twente, Physics of Fluids, The Netherlands, Physics of Fluids Group, Faculty of Science and Technology, University of Twente

  • Chao Sun

    Physics of Fluids Group, Faculty of Science and Technology, University of Twente

  • Detlef Lohse

    Physics of Fluids, Faculty of Science and Technology, University of Twente, Physics of Fluids Group, Faculty of Science and Technology, University of Twente, the Netherlands, University of Twente, Physics of Fluids, The Netherlands, Physics of Fluids-University of Twente, Twente, University of Twente, The Netherlands, Physics of Fluids, University of Twente, Physics of Fluids Group, Faculty of Science and Technology, University of Twente