DEPOSITION OF COLLOIDAL PARTICLES IN STAGNATION-POINT FLOW

A theoretical analysis of the deposition of colloidal particles under plane stagnation-point flow is presented. The effect of interfacial convection and attractive double-layer forces on the deposition kinetics is discussed. It is found that there is a considerable increase in the deposition rate as the double-layer thickness increases and also as the influence of interfacial convection increases (i.e., as the Peclet number increases). Asymptotic analytical solutions to the convective-diffusion equation (which includes electrical double-layer and van der Waals forces along with fluid convection) have been obtained and are shown to be accurate for large values of the double-layer thickness and Peclet number (i.e. when significant deposition rates may be expected). The results presented here eliminate some of the restrictions imposed by a previously available analytical solution, which is valid only for small electrical double-layer thickness, large potential barriers and low interfacial convection. In situations where these latter conditions hold, one may expect only very small values for the deposition rate (in contrast to the conditions considered in the present paper).