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Title: Mixing and segregation of granular materials in chute flows

Abstract

Mixing of granular solids is invariably accompanied by segregation, however, the fundamentals of the process are not well understood. We analyze density and size segregation in a chute flow of cohesionless spherical particles by means of computations and theory based on the transport equations for a mixture of nearly elastic particles. Computations for elastic particles (Monte Carlo simulations), nearly elastic particles, and inelastic, frictional particles (particle dynamics simulations) are carried out. General expressions for the segregation fluxes due to pressure gradients and temperature gradients are derived. Simplified equations are obtained for the limiting cases of low volume fractions (ideal gas limit) and equal sized particles. Theoretical predictions of equilibrium number density profiles are in good agreement with computations for mixtures of equal sized particles with different density for all solids volume fractions, and for mixtures of different sized particles at low volume fractions ([nu][lt]0.2), when the particles are elastic or nearly elastic. In the case of inelastic, frictional particles the theory gives reasonable predictions if an appropriate effective granular temperature is assumed. The relative importance of pressure diffusion and temperature diffusion for the cases considered is discussed. [copyright] [ital 1999 American Institute of Physics.]

Authors:
 [1];  [2];  [3]
  1. (Department of Chemical Engineering, Indian Institute of Technology---Bombay, Powai, Mumbai 400076 (India))
  2. (Department of Chemical Engineering, University of Pittsburgh, Pittsburgh, Pennsylvania 15261 (United States))
  3. (Department of Chemical Engineering, Northwestern University, Evanston, Illinois 60208 (United States))
Publication Date:
OSTI Identifier:
6470940
Alternate Identifier(s):
OSTI ID: 6470940
Resource Type:
Journal Article
Journal Name:
Chaos
Additional Journal Information:
Journal Volume: 9:3; Journal ID: ISSN 1054-1500
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; GRANULAR MATERIALS; MIXING; MONTE CARLO METHOD; SEGREGATION; TRANSPORT THEORY; CALCULATION METHODS; MATERIALS 661300* -- Other Aspects of Physical Science-- (1992-)

Citation Formats

Khakhar, D.V., McCarthy, J.J., and Ottino, J.M. Mixing and segregation of granular materials in chute flows. United States: N. p., 1999. Web. doi:10.1063/1.166433.
Khakhar, D.V., McCarthy, J.J., & Ottino, J.M. Mixing and segregation of granular materials in chute flows. United States. doi:10.1063/1.166433.
Khakhar, D.V., McCarthy, J.J., and Ottino, J.M. Wed . "Mixing and segregation of granular materials in chute flows". United States. doi:10.1063/1.166433.
@article{osti_6470940,
title = {Mixing and segregation of granular materials in chute flows},
author = {Khakhar, D.V. and McCarthy, J.J. and Ottino, J.M.},
abstractNote = {Mixing of granular solids is invariably accompanied by segregation, however, the fundamentals of the process are not well understood. We analyze density and size segregation in a chute flow of cohesionless spherical particles by means of computations and theory based on the transport equations for a mixture of nearly elastic particles. Computations for elastic particles (Monte Carlo simulations), nearly elastic particles, and inelastic, frictional particles (particle dynamics simulations) are carried out. General expressions for the segregation fluxes due to pressure gradients and temperature gradients are derived. Simplified equations are obtained for the limiting cases of low volume fractions (ideal gas limit) and equal sized particles. Theoretical predictions of equilibrium number density profiles are in good agreement with computations for mixtures of equal sized particles with different density for all solids volume fractions, and for mixtures of different sized particles at low volume fractions ([nu][lt]0.2), when the particles are elastic or nearly elastic. In the case of inelastic, frictional particles the theory gives reasonable predictions if an appropriate effective granular temperature is assumed. The relative importance of pressure diffusion and temperature diffusion for the cases considered is discussed. [copyright] [ital 1999 American Institute of Physics.]},
doi = {10.1063/1.166433},
journal = {Chaos},
issn = {1054-1500},
number = ,
volume = 9:3,
place = {United States},
year = {1999},
month = {9}
}