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

We present experimental results on dense corn-starch suspensions as examples of non-Brownian, nearly hard particles that undergo continuous and discontinuous shear thickening (DST) at intermediate and high densities, respectively. Our results offer strong support for recent theories involving a stre...

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Bibliographic Details
Published in:Journal of rheology (New York : 1978) 2016-09, Vol.60 (5), p.905-916
Main Authors: Hermes, Michiel, Guy, Ben M., Poon, Wilson C. K., Poy, Guilhem, Cates, Michael E., Wyart, Matthieu
Format: Article
Language:English
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Summary:We present experimental results on dense corn-starch suspensions as examples of non-Brownian, nearly hard particles that undergo continuous and discontinuous shear thickening (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.
ISSN:0148-6055
1520-8516
DOI:10.1122/1.4953814