Orientation Dynamics of Sedimenting Anisotropic Particles in Turbulence

Prateek Anand, Samriddhi Sankar Ray, and Ganesh Subramanian
Phys. Rev. Lett. 125, 034501 – Published 13 July 2020
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Abstract

We examine the dynamics of small anisotropic particles (spheroids) sedimenting through homogeneous isotropic turbulence using direct numerical simulations and theory. The gravity-induced inertial torque acting on sub-Kolmogorov spheroids leads to pronouncedly non-Gaussian orientation distributions localized about the broadside-on (to gravity) orientation. Orientation distributions and average settling velocities are obtained over a wide range of spheroid aspect ratios, Stokes, and Froude numbers. Orientational moments from the simulations compare well with analytical predictions in the inertialess rapid-settling limit, with both exhibiting a nonmonotonic dependence on spheroid aspect ratio. Deviations arise at Stokes numbers of order unity due to a spatially inhomogeneous particle concentration field resulting from a preferential sweeping effect; as a consequence, the time-averaged particle settling velocities exceed the orientationally averaged estimates.

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  • Received 23 August 2019
  • Revised 12 May 2020
  • Accepted 19 June 2020

DOI:https://doi.org/10.1103/PhysRevLett.125.034501

© 2020 American Physical Society

Physics Subject Headings (PhySH)

Fluid DynamicsNonlinear DynamicsStatistical Physics & Thermodynamics

Authors & Affiliations

Prateek Anand1,*, Samriddhi Sankar Ray2,†, and Ganesh Subramanian1,‡

  • 1Jawaharlal Nehru Centre for Advanced Scientific Research, Bangalore 560064, India
  • 2International Centre for Theoretical Sciences, Tata Institute of Fundamental Research, Bangalore 560089, India

  • *prateek@jncasr.ac.in
  • samriddhisankarray@gmail.com
  • sganesh@jncasr.ac.in

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Issue

Vol. 125, Iss. 3 — 17 July 2020

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