Theory for the coalescence of viscous lenses

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

Metastable States of Water Aerosols: Comparison by Experiment

Free energy of water aerosol plasma was calculated using the Debye–Hückel method. It was established that free energies of droplets, ions and simultaneously of all charged particles had local minima (metastable states) at certain concentrations and charges of particles. The calculation results were confirmed by experimental data taken from the literature on a droplet cluster in water vapor and droplet structures in water fog. The possible connection of metastable states with the phenomenon of drop coalescence and rain formation in real clouds, as well as with the generation of stable spatially arranged drop structures, has been indicated.