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Shear zones and wall slip in the capillary flow of concentrated colloidal suspensions

Lucio Isa·Rut Besseling·Wilson C K Poon
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Abstract

We image the flow of a nearly random close packed, hard-sphere colloidal suspension (a `paste') in a square capillary using confocal microscopy. The flow consists of a `plug' in the center while shear occurs localized adjacent to the channel walls, reminiscent of yield-stress fluid behavior. However, the observed scaling of the velocity profiles with the flow rate strongly contrasts yield-stress fluid predictions. Instead, the velocity profiles can be captured by a theory of stress fluctuations originally developed for chute flow of dry granular media. We verified this behavior both for smooth and rough boundary conditions.

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Lucio Isa, Rut Besseling, Wilson C K Poon. 2007-02-27. Shear zones and wall slip in the capillary flow of concentrated colloidal suspensions. https://doi.org/10.1103/physrevlett.98.198305

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