Nonmonotonic settling of a sphere in a cornstarch suspension.
Cornstarch suspensions exhibit remarkable behavior. Here, we present two unexpected observations for a sphere settling in such a suspension: In the bulk of the liquid the velocity of the sphere oscillates around a terminal value, without damping. Near the bottom the sphere comes to a full stop, but then accelerates again toward a second stop. This stop-go cycle is repeated several times before the object reaches the bottom. We show that common shear thickening or linear viscoelastic models cannot account for the observed phenomena, and propose a minimal jamming model to describe the behavior at the bottom.
Physics of Fluids group, University of Twente, PO Box 217, NL-7500 AE Enschede, The Netherlands.
Stefan
S
von Kann
Jacco H
JH
Snoeijer
Detlef
D
Lohse
Devaraj
D
van der Meer