Theory for the coalescence of viscous lenses

Drop coalescence occurs through the rapid growth of a liquid bridge that connects two drops. At early times after contact, dynamics is typically self-similar, with details depending on geometry and viscosity liquid. In this paper we analyse two-dimensional viscous drops float quiescent deep pool; such are called lenses. The analysis based thin-sheet equations, which were recently shown to accurately capture experiments lens coalescence. It found follows self-similar solution at leading order, but, large-scale boundary conditions drop, significant corrections may arise solution. This studied in detail using numerical simulations matched asymptotics. We show can involve global translation drops, feature confirmed experimentally.