Viscous resuspension

The resuspension of a settled layer of particles in a shear flow, typically associated with turbulence, has also been found to occur under viscous conditions (Gadala-Maria, F.A., 1979, Ph.D. Thesis, Stanford University). In this work we demonstrate that viscous resuspension, characterized by the equilibrium height achieved by an initially settled bed of particles expanding in the presence of an applied shear stress, results from a balance between the downward flux of particles due to gravity and an upward flux arising from shear-induced particle diffusion. Predictions of this equilibrium height using independent measurements of the shear-induced diffusion coefficient are shown to be in approximate agreement with experimental observations.