Universality in the viscous-to-inertial coalescence of liquid droplets.

Xia, Xi; He, Chengming; Zhang, Peng · Proc Natl Acad Sci U S A · 2019

basic_science · Level V

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Abstract

We present a theory on the coalescence of 2 spherical liquid droplets that are initially stationary. The evolution of the radius of a liquid neck formed upon coalescence was formulated as an initial value problem and then solved to yield an exact solution without free parameters, with its 2 asymptotic approximations reproducing the well-known scaling relations in the inertially limited viscous and inertial regimes. The viscous-to-inertial crossover observed in previous research is also recovered by the theory, rendering the collapse of data of different viscosities onto a single curve.