A MODEL OF SETTLING VELOCITY

Attention is drawn to the lack of a successful theoretical model for c alculation of the effect of solids concentration on the settling veloc ity of particles from suspension. The principal challenge to formulati on of a model is solution of the equations of fluid motion through an ensemble of solid particles which are randomly distributed to space. A new theoretical model which addresses this difficulty is presented. I t is based on permeation of the fluid through a structure composed of cells each of which consists of a single spherical particle and an ass ociated body of fluid. The quantity of fluid in each cell is a random variable. Using this model, the settling velocity of a suspension at s ubstantial volume fraction can be calculated without resort to empiric ally determined factors. Good agreement with experimental settling vel ocities is obtained. (C) 1997 Elsevier Science Ltd.