Clustering and relative velocities of heavy particles under gravitational settling in isotropic turbulent flows

Guodong Jin; Guo-Wei He

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arXiv · 1507.07278

Clustering and relative velocities of heavy particles under gravitational settling in isotropic turbulent flows

Guodong Jin·Guo-Wei He

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Abstract

Spatial clustering and intermittency in the relative velocity of heavy particles of the same size settling in turbulent flows can be strongly affected by gravity. We present a model for the timescale of the fluid velocity gradient seen by particle pairs and propose an effective Kubo number based on this timescale to explain the mechanism of gravity-enhanced clustering. We explore the mechanisms of the gravity-induced reduction or enhancement of the intermittency in the particle radial relative velocity (RRV) at different Stokes numbers based on backward-in-time relative dispersion and preferential sampling of the fluid field. These effects of gravity on clustering and the RRV must be parameterized in the geometric collision kernel.

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Guodong Jin, Guo-Wei He. 2015-07-27. Clustering and relative velocities of heavy particles under gravitational settling in isotropic turbulent flows. https://arxiv.org/abs/1507.07278

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