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The non-Newtonian rheology of dilute colloidal suspensions

Bergenholtz, J. and Brady, J. F. and Vicic, M. (2002) The non-Newtonian rheology of dilute colloidal suspensions. Journal of Fluid Mechanics, 456 . pp. 239-275. ISSN 0022-1120. https://resolver.caltech.edu/CaltechAUTHORS:BERjfm02

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Abstract

The non-Newtonian rheology is calculated numerically to second order in the volume fraction in steady simple shear flows for Brownian hard spheres in the presence of hydrodynamic and excluded volume interactions. Previous analytical and numerical results for the low-shear structure and rheology are confirmed, demonstrating that the viscosity shear thins proportional to Pe2, where Pe is the dimensionless shear rate or Péclet number, owing to the decreasing contribution of Brownian forces to the viscosity. In the large Pe limit, remnants of Brownian diffusion balance convection in a boundary-layer in the compressive region of the flow. In consequence, the viscosity shear thickens when this boundary-layer coincides with the near-contact lubrication regime of the hydrodynamic interaction. Wakes are formed at large Pe in the extensional zone downstream from the reference particle, leading to broken symmetry in the pair correlation function. As a result of this asymmetry and that in the boundary-layer, finite normal stress differences are obtained as well as positive departures in the generalized osmotic pressure from its equilibrium value. The first normal stress difference changes from positive to negative values as Pe is increased when the hard-sphere limit is approached. This unusual effect is caused by the hydrodynamic lubrication forces that maintain particles in close proximity well into the extensional quadrant of the flow. The study demonstrates that many of the non-Newtonian effects observed in concentrated suspensions by experiments and by Stokesian dynamics simulations are present also in dilute suspensions.


Item Type:Article
Additional Information:"Reprinted with the permission of Cambridge University Press." (Received December 4 2000) (Revised October 11 2001) Published online 9 April 2002 This work was supported in part by a grant from IFPRI.
Subject Keywords:STOKESIAN DYNAMICS SIMULATION; SHEAR-THICKENING DILATANCY; HARD-SPHERE SUSPENSIONS; BROWNIAN SUSPENSIONS; CONCENTRATED SUSPENSIONS; HUGGINS COEFFICIENT; RIGID SPHERES; SOLID SPHERES; BULK STRESS; DISPERSIONS
Record Number:CaltechAUTHORS:BERjfm02
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:BERjfm02
Alternative URL:http://dx.doi.org/10.1017/S0022112001007583
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:1585
Collection:CaltechAUTHORS
Deposited By: Archive Administrator
Deposited On:01 Feb 2006
Last Modified:02 Oct 2019 22:44

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