Role of inertial lift in elutriating particles according to their density

A Reflux Classifier involves the liquid fluidization of particles into a set of parallel inclined channels. Closely spaced inclined channels promote a combination of laminar flow and a high shear rate, which in turn promote the elutriation of the particles according to their density. The hydrodynamics of the particle transport within the inclined channels was examined theoretically by combining established equations for describing the fluid flow, the terminal velocity of a particle, and the shear induced inertial lift, with no adjustable parameters. The theoretical calculations provided excellent agreement with a comprehensive experimental data set, demonstrating the significance of the inertial lift force that arises at a high shear rate under the condition of laminar flow. Complex features of the experimental data were described theoretically. This work explains how it is possible to elutriate particles according to their density, with the effects of particle size suppressed. A remarkable convergence of several criteria was found to be necessary for achieving the reported phenomena.