Hydrodynamics of Particles at an Oil-Water Interface

Archit Dani, Geoff Keiser, Mohsen Yeganeh, Charles Maldarelli

Research output: Contribution to journalArticlepeer-review

53 Scopus citations


This study is a theoretical and experimental investigation of the hydrodynamics of the mutual approach of two floating spherical particles moving along an oil-water interface. An analytical expression is obtained for the (inertialess) Stokes drag for an isolated particle translating on a flat interface as a function of the immersion depth into the water phase for the case in which the viscosity of the oil is much larger than that of the water. An approximation for the viscous drag due to the mutual approach of identical spheres is formulated as the product of the isolated drag multiplied by the resistance of approaching spheres in an infinite medium. Experiments are undertaken on the capillary attraction of large, millimeter-sized Teflon spheres floating at the interface between a very viscous oil and water. With the use of image visualization and particle tracking, the separation distance as a function of time [l(t)] is measured along with the immersion depth and predicted by setting the capillary attraction force equal to the viscous drag resistance. The excellent agreement validates the approximating formula.

Original languageEnglish (US)
Pages (from-to)13290-13302
Number of pages13
Issue number49
StatePublished - Oct 21 2015
Externally publishedYes

Bibliographical note

Publisher Copyright:
© 2015 American Chemical Society.


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