title: Stress hysteresis as the cause of persistent holes in particulate suspensions.
abstract: Concentrated particulate suspensions under vibrations can support stable, localized, vertically oriented free surfaces. The most robust of these structures are persistent holes: deep and stable depressions of the interface. Using a reduced model of the hydrodynamics we show that a rheology with hysteresis can lead to motion opposite to the time-averaged applied force. Moreover, we show experimentally that particulate suspensions of cornstarch in water exhibits hysteresis in the shear-rate response to an applied sinusoidal stress. The results of our model and our experiments suggest that hysteresis accounts for the outward force needed to support persistent holes.
authors.affiliation: Department of Physics and Center for the Study of Complex Systems, Randall Laboratory, University of Michigan, Ann Arbor, Michigan 48109, USA. rddeegan@umich.edu
authors.forename: Robert D
authors.initials: RD
authors.lastname: Deegan