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arXiv · 1412.5333

S-Shaped Flow Curves of Shear Thickening Suspensions: Direct Observation of Frictional Rheology

Zhongcheng Pan·Henri de Cagny·Bart Weber·Daniel Bonn
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Abstract

We study the rheological behavior of concentrated granular suspensions of simple spherical particles. Under controlled stress, the system exhibits an S-shaped flow curve (stress vs. shear rate) with a negative slope in between the low-viscosity Newtonian regime and the shear thickened regime. Under controlled shear rate, a discontinuous transition between the two states is observed. Stress visualization experiments with a novel fluorescent probe suggest that friction is at the origin of shear thickening. Stress visualization shows that the stress in the system remains homogeneous (no shear banding) if a stress is imposed that is intermediate between the high and low-stress branches. The S-shaped shear thickening is then due to the discontinuous formation of a frictional force network between particles upon increasing the stress.

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Zhongcheng Pan, Henri de Cagny, Bart Weber, Daniel Bonn. 2015-06-03. S-Shaped Flow Curves of Shear Thickening Suspensions: Direct Observation of Frictional Rheology. https://doi.org/10.1103/physreve.92.032202

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