Suppression of short-term oscillations in falling droplets by viscoelastic interfacial layers
Phys. Rev. Fluids 10, 113601 – Published 12 November, 2025
DOI: https://doi.org/10.1103/93gd-fjll
Abstract
Material assemblies at liquid-fluid interfaces on the microscale control the macroscopic behavior of multiphase processes by reducing interfacial tension, generating Marangoni stresses and introducing surface viscoelasticity. These interfacial effects directly impact processes such as energy extraction, drug formulation, and advanced material synthesis. Here we experimentally investigate the dynamics of falling silica dispersion droplets in a stationary oil phase containing surfactants. While oblate-prolate oscillations of Newtonian droplets are well documented for clean interfaces, we report that the in situ formation of a highly condensed interfacial material rapidly transforms the droplet into an oblate shape and attenuates its oscillations. The observed suppression of oscillations is consistent with theoretical predictions for droplets submerged in immiscible fluids with inextensible interfaces. These results highlight the impact of interfacial viscoelasticity on falling droplet dynamics, driven by the in situ formation of a viscoelastic emulsion layer at the nanoparticle dispersion-micellar solution interface.
