Self-similar liquid lens coalescence

Michiel A. Hack*, Walter Tewes, Qingguang Xie, Charu Datt, Kirsten Harth, Jens Harting, Jacco H. Snoeijer

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

21 Citations (Scopus)
56 Downloads (Pure)


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 prewetted 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 structures 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.
Original languageEnglish
Article number194502
JournalPhysical review letters
Issue number19
Publication statusPublished - 14 May 2020


  • Drop coalescence


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