Hydrodynamic segregation in a bidisperse colloidal suspension in microchannel flow: A theoretical study.

Abstract

Colloids in suspension exhibit shear-induced migration towards regions of low viscous shear. In dense bidisperse colloidal suspensions under pressure driven flow large particles can segregate in the center of a microchannel and the suspension partially demixes. To develop a theoretical understanding of these effects, we formulate a phenomenological model for the particle currents based on the work of Phillips et al. [Phys. Fluids 4, 30 (1992)]. We also simulate hard spheres under pressure-driven flow in two and three dimensions using the mesoscale simulation technique of multi-particle collision dynamics. Using a single fit parameter for the intrinsic diffusivity, our theory accurately reproduces the simulated density profiles across the channel. We present a detailed parameter study on how a monodisperse suspension enriches the channel center and quantitatively confirm the experimental observation that a binary colloidal mixture partially segregates into its two species. In particular, we always find a strong accumulation of large particles in the center. Qualitative differences between two and three dimensions reveal that collective diffusion is more relevant in two dimensions.

DOI: 10.1063/1.4921800

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Cite this paper

@article{Kanehl2015HydrodynamicSI, title={Hydrodynamic segregation in a bidisperse colloidal suspension in microchannel flow: A theoretical study.}, author={Philipp Kanehl and Holger Stark}, journal={The Journal of chemical physics}, year={2015}, volume={142 21}, pages={214901} }