title: Symmetric and asymmetric coalescence of drops on a substrate.
abstract: The coalescence of viscous drops on a substrate is studied experimentally and theoretically. We consider cases where the drops can have different contact angles, leading to a very asymmetric coalescence process. Side view experiments reveal that the "bridge" connecting the drops evolves with self-similar dynamics, providing a new perspective on the coalescence of sessile drops. We show that the universal shape of the bridge is accurately described by similarity solutions of the one-dimensional lubrication equation. Our theory predicts that, once the drops are connected on a microscopic scale, the bridge grows linearly in time with a strong dependence on the contact angles. Without any adjustable parameters, we find quantitative agreement with all experiments.
authors.affiliation: Physics of Fluids Group, MESA+Institute for Nanotechnology, JM Burgers Centre for Fluid Dynamics, University of Twente, PO Box 217, 7500 AE Enschede, The Netherlands.
authors.forename: J F
authors.initials: JF
authors.lastname: Hernández-Sánchez
authors.forename: L A
authors.initials: LA
authors.lastname: Lubbers
authors.forename: A
authors.initials: A
authors.lastname: Eddi
authors.forename: J H
authors.initials: JH
authors.lastname: Snoeijer