VISCOUS RESUSPENSION OF A SEDIMENT WITHIN A LAMINAR AND STRATIFIED FLOW

Resuspension, under the action of shear, of an initially settled bed of particles has been observed not only in turbulent flows but also under laminar conditions. By applying a model developed previously, we investigate theoretically such a resuspension in a fully-developed Hagen-Poiseuille channel flow and in a corresponding gravity-driven film flow along an inclined plate. It is found that, in the former case, the region occupied by the suspension cannot extend beyond the plane of zero shear stress, while for the film flow, a critical value for the feed concentration is predicted beyond which steady-state operation is no longer possible. Experimental observations in a channel flow are found to be in good agreement with the theory. © 1990.