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

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Original languageEnglish
Article number198305
Pages (from-to)-
Number of pages4
JournalPhysical Review Letters
Issue number19
Publication statusPublished - 11 May 2007


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 both for smooth and rough walls.

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