EFFECT OF VELOCITY-FIELDS ON BINARY AND INTERFACIAL COALESCENCE

Analytical equations allowing for the van der Waals force of attraction are derived for the variation in film thickness with time during viscous drainage of a planar film of expanding area formed between two small equisized liquid drops (or bubbles) which are initially spherical and approach with a finite velocity under the action of a constant external force. Alternatively, the initial drainage can be considered to be inertial in an expanding planar film. The equations are also applicable to the approach of a drop (or bubble) to a plane or deformable interface. The analysis is extended to include the collision of two oscillating liquid drops in a gravity field. Furthermore, analytical equations are also derived for the variation in film thickness with time during the approach and separation of two initially spherical small equisized liquid drops in a shear field. The predicted coalescence times agree with the experimental values reported in literature. © 1993 Academic Press, Inc.