Effect of Electric Double Layer Repulsion on Oil Droplet Coalescence Process

Abstract

Film drainage between two droplets approaching each other at constant velocity under the influence of electric double layer repulsion is studied systematically. Based on the lubrication equations, a mathematical model is given to govern the evolution of film drainage between two oil droplets. This model consists of three coupled fourth-order nonlinear parabolic partial differential equations describing the dynamic evolution of the film thickness, film pressure and surfactant interfacial concentration. The numerical method used is the finite element method. The main objective of this research work is to modify the film pressure equation by considering the electric double layer repulsion. The effects of electric double layer repulsion and viscosity ratio on film drainage are investigated theoretically.

Drop coalescence in technical liquid/liquid applications: a review on experimental techniques and modeling approaches

“…Although these and other complex models (Jeffreys and Hawksley 1965b, Burrill and Woods 1969, 1973a, Chesters and Hofman 1982, Chen 1985, Li 1994, Saboni et al 1995, Jeelani and Hartland 1998, Bazhlekov et al 2000, Hagesaether et al 1999, Klaseboer et al 2000, Yeo et al 2003, Baldessari and Leal 2006, Toro-Mendoza and Petsev 2010, Zhang et al 2010 are able to model radial profiles of the draining film, the simplification of the complex 3D flow to two dimensions (h, r) is inaccurate because the film drainage is at least unsymmetrical in the moment just before film rupture. Consequently, the description of film drainage and the a priori prediction of coalescence are still challenging tasks for future investigations.…”