HYDRODYNAMIC ASPECTS OF FLOCCULATION.

Abstract

In the classical analyses of both Brownian (perikinetic) and velocity gradient (orthokinetic) flocculation particle encounters in sufficiently dilute systems are treated as binary collisions between rigid spheres. Modern analyses recognize that the motion of two neighboring particles suspended in a viscous fluid is different from that resulting by combining their isolated motions. Modern treatments include forces of hydrodynamic origin that qualitatively tend to inhibit encounters between particle pairs. Incorporating the hydrodynamic forces along with the external field forces yields a more realistic description of the total encounter process. This has not only led to better understanding of flocculation, but to important advances in describing the rheological properties of suspensions as well.