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Coalescence of droplets due to a constant force interaction in a quiescent viscous fluid

John M. Frostad1,*, Alexandra Paul1,2, and L. Gary Leal1

  • 1Department of Chemical Engineering, University of California, Santa Barbara, Santa Barbara, California 93106, USA
  • 2Department of Biophysical Chemistry, Saarland University, Saarbrucken 66123, Germany

  • *Corresponding author: frostad@engineering.ucsb.edu
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Phys. Rev. Fluids 1, 033904 – Published 25 July, 2016

DOI: https://doi.org/10.1103/PhysRevFluids.1.033904

Abstract

A cantilevered-capillary force apparatus is used to study the time scale for the coalescence of two droplets compressed together with a constant force. Power-law trends for the coalescence time as a function of droplet radius and compression force are experimentally measured. The measurements are compared against several different scaling theories from the literature. One of the existing theories is found to correctly predict the dependence on the droplet radius, but all of the theories overpredict the dependence on the force. A transition is also observed in the measured drainage time from a small variation around a single deterministic value for droplets with a radius of 125 µm or less to a broad distribution of drainage times for droplets with a radius of 150 µm. A qualitative explanation for this transition is provided via scaling arguments.

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Information

Phys. Rev. Fluids 1, 033904– Published 25 July, 2016
  • Received 14 March 2016
Article part of CHORUS

©2016 American Physical Society

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