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Dynamic structure factor study of diffusion in strongly sheared suspensions

Leshansky, Alexander M. and Brady, John F. (2005) Dynamic structure factor study of diffusion in strongly sheared suspensions. Journal of Fluid Mechanics, 527 . pp. 141-169. ISSN 0022-1120. http://resolver.caltech.edu/CaltechAUTHORS:LESjfm05

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Abstract

Diffusion of neutrally buoyant spherical particles in concentrated monodisperse suspensions under simple shear flow is investigated. We consider the case of non-Brownian particles in Stokes flow, which corresponds to the limits of infinite Péclet number and zero Reynolds number. Using an approach based upon ideas of dynamic light scattering we compute self- and gradient diffusion coefficients in the principal directions normal to the flow numerically from Accelerated Stokesian Dynamics simulations for large systems (up to 2000 particles). For the self-diffusivity, the present approach produces results identical to those reported earlier, obtained by probing the particles' mean-square displacements (Sierou & Brady, J. Fluid Mech. vol. 506, 2004 p. 285). For the gradient diffusivity, the computed coefficients are in good agreement with the available experimental results. The similarity between diffusion mechanisms in equilibrium suspensions of Brownian particles and in non-equilibrium non-colloidal sheared suspensions suggests an approximate model for the gradient diffusivity: ${\textsfbi D}^\triangledown\,{\approx}\,{\textsfbi D}^s/S^{eq}(0)$, where ${\textsfbi D}^s$ is the shear-induced self-diffusivity and $S^{eq}(0)$ is the static structure factor corresponding to the hard-sphere suspension at thermodynamic equilibrium.


Item Type:Article
Additional Information:"Reprinted with the permission of Cambridge University Press." (Received 30 April 2004 and in revised form 29 September 2004) The authors would like to thank Ileana Carpen for providing results of the Brownian dynamics simulations. A.M.L. also acknowledges the support of the Lester Deutch Foundation.
Record Number:CaltechAUTHORS:LESjfm05
Persistent URL:http://resolver.caltech.edu/CaltechAUTHORS:LESjfm05
Alternative URL:http://dx.doi.org/10.1017/S0022112004002903
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:287
Collection:CaltechAUTHORS
Deposited By: Archive Administrator
Deposited On:17 May 2005
Last Modified:26 Dec 2012 08:39

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