Self-Similar Liquid Lens Coalescence

Abstract

A basic feature of liquid drops is that they can merge upon contact to form a larger drop. In spite of its importance to various applications, drop coalescence on pre-wetted substrates has received little attention. Here, we experimentally and theoretically reveal the dynamics of drop coalescence on a thick layer of a low-viscosity liquid. It is shown that these so-called "liquid lenses" merge by the self-similar vertical growth of a bridge connecting the two lenses. Using a slender analysis, we derive similarity solutions corresponding to the viscous and inertial limits. Excellent agreement is found with the experiments without any adjustable parameters, capturing both the spatial and temporal structure of the flow during coalescence. Finally, we consider the crossover between the two regimes and show that all data of different lens viscosities collapse on a single curve capturing the full range of the coalescence dynamics.

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Cited by in corpus (8)

• On droplets coalescence in a quasi-2D fluid
• Coalescence of Islands in Freely-Suspended Smectic Films
• Engulfment of a drop on solids coated by thin and thick fluid films
• Capillary filling in drop merging: dynamics of the four-phase contact point
• Singular jets in compound drop impact
• Interfacial dripping faucet: generating monodisperse liquid lenses
• Dynamics of capillary coalescence and breakup: quasi-two-dimensional nematic and isotropic droplets
• Theory for the coalescence of viscous lenses