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arXiv · 1511.08011

Unsteady flow and particle migration in dense, non-Brownian suspensions

Michiel Hermes·Ben M. Guy·Guilhem Poy·Michael E. Cates·Matthieu Wyart·Wilson C. K. Poon
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Abstract

We present experimental results on dense corn-starch suspensions as examples of non-Brownian, nearly-hard particles that undergo continuous and discontinuous shear thickening (CST and DST) at intermediate and high densities respectively. Our results offer strong support for recent theories involving a stress-dependent effective contact friction among particles. We show however that in the DST regime, where theory might lead one to expect steady-state shear bands oriented layerwise along the vorticity axis, the real flow is unsteady. To explain this, we argue that steady-state banding is generically ruled out by the requirement that, for hard non-Brownian particles, the solvent pressure and the normal-normal component of the particle stress must balance separately across the interface between bands. (Otherwise there is an unbalanced migration flux.) However, long-lived transient shear-bands remain possible.

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Michiel Hermes, Ben M. Guy, Guilhem Poy, Michael E. Cates, Matthieu Wyart, Wilson C. K. Poon. 2016-05-18. Unsteady flow and particle migration in dense, non-Brownian suspensions. https://doi.org/10.1122/1.4953814

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