THEORY OF DETACHMENT OF COLLOIDAL PARTICLES FROM FLAT SURFACES EXPOSED TO FLOW

Theoretical models are presented for the detachment of colloidal particles from solid surfaces exposed to shear flow. The models are most relevant to cases of hard, spherical particles, which are small enough to display Brownian motion. It is concluded that the componet of hydrodynamic force acting parallel to a sheared wall is usually much larger than the lifting force. Thus, in most cases, one can expect the downstream component of force to govern the critical or rate-determining step in the process of entrainment. Alternative limiting modes of incipient motion, e. g. , rolling, sliding, and lifting, can be distinguished, based on the dependency of the shear stress required for detachment on the size of particles.