The effect of bulk motion on coagulation rates of colloidal dispersions

Following the work in 1917 of Smoluchowski, the theory of coagulation of micronsized particles progressed very little until quantitative estimates were possible for induced-dipole attraction and electrostatic double-layer repulsion. A second increase in our understanding of coagulation of colloids has been achieved through application of recent results in fluid mechanics concerning the viscous forces operative between two particles in relative motion.In this survey the essential features of recent theories and experiments of the behavior of spherical of hydrophobic colloids in aqueous suspensions are outlined. Departures from earlier theories are reviewed, and attempts to incorporate simultaneously the effects of bulk flow and of Brownian motion are described.