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Title:Particle dispersion in isotropic turbulence under influence of non-stokesian drag and gravitational settling
Author(s):Mei, Renwei; Adrian, Ronald J.; Hanratty, Thomas J.
Subject(s):Particle Dispersion
Isotropic Turbulence
Non-stokesian Drag
Gravitational Settling
Abstract:Dispersion of heavy particles under the influence of nonlinear drag and arbitrary settling velocity in isotropic turbulence is studied. When the settling velocity of the particle due to the gravitational force is comparable to or larger than the turbulence velocity, the particle time constants of the two components of the fluctuating velocity, parallel and perpendicular to the body force, are different due to the large settling velocity and the non linearity in the drag. Reeks' ( 1977) analysis is extended to include the effect of anisotropic particle time constants on the dispersion of particles. The behavior of the particle motion at zero settling velocity is examined in the non-Stokesian drag range. An interpolation scheme based on the results at zero and large settling velocity is proposed to obtain the settling velocity and the particle time constants, which cannot be determined using Reeks' analysis, in the non-Stokesian drag range. A Monte Carlo simulation is performed for a large number of particles in a pseudo turbulence described by a Gaussian distribution and Kraichnan's ( 1970) energy spectrum. Excellent agreement between the nonlinear analysis and the simulation is obtained for zero, intermediate and large settling velocities in the nonlinear drag range. The fluid turbulence and the fluctuations of the particle velocity are found to follow Gaussian distributions in the nonlinear drag range. The slip velocity at zero settling velocity follows a Maxwellian distribution. The fluid and particle turbulence have significant effects on the particle time constants and the particle settling velocity in the nonlinear drag range which in turn affects the dispersion of particles. These effects are quantified by using a Froude number, Fg, a particle inertia parameter in the Stokesian drag range, βs, and a turbulence particle Reynolds number, Reu0, defined with the fluid turbulence intensity and the particle diameter.
Issue Date:1993-11
Publisher:Department of Theoretical and Applied Mechanics. College of Engineering. University of Illinois at Urbana-Champaign
Series/Report:TAM R 735
Genre:Technical Report
Rights Information:Copyright 1993 Board of Trustees of the University of Illinois
Date Available in IDEALS:2021-11-04

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  • Technical Reports - Theoretical and Applied Mechanics (TAM)
    TAM technical reports include manuscripts intended for publication, theses judged to have general interest, notes prepared for short courses, symposia compiled from outstanding undergraduate projects, and reports prepared for research-sponsoring agencies.

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