78th Annual Meeting of the APS Division of Fluid Dynamics (Nov 23 — 25, 2025)
P037: Hollow Droplets Meet a Thin Film
Hollow droplets, comprising a liquid shell encapsulating a gas bubble, exhibit core-shell morphologies with impact dynamics fundamentally distinct from those of single-phase droplets. These droplets play pivotal roles in both natural and advanced engineering processes, including aerosol generation, 3D printing, and thermal spray coating. Using high-speed imaging, we reveal the full sequence of hollow droplet impact on a thin liquid film, including splashing and counter-jet formation, governed by the intricate interplay between droplet impact dynamics and internal bubbles. By introducing combinations of modified non-dimensional numbers, we establish a unified scaling for the mechanics underlying these phenomena. This previously unexplored regime offers new insights into fluid fragmentation pathways and provides a quantitative framework for interpreting and controlling splash phenomena across disciplines.
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