Hermes, MichielGuy, Ben M.Poon, Wilson C. K.Poy, GuilhemCates, Michael E.Wyart, Matthieu2016-10-182016-10-182016-10-18201610.1122/1.4953814https://infoscience.epfl.ch/handle/20.500.14299/130525WOS:000384392300008We 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. (C) 2016 The Society of Rheology.text::journal::journal article::research article