High-velocity droplet impact dynamics on lubricant-infused surfaces*

Since the pioneering work of Worthington in 1876, engineers and physicists including the public have been fascinated by the mesmerizing images of the crown that forms when a droplet impacts a rigid surface. Setting the beauty aside, droplet impact and breakup has broad technological implications in agriculture, inkjet printing, spray coating, combustion, and forensic science. The dynamics of a droplet impacting a rigid surface is determined by the complex interplay between surface tension, viscosity, inertia, and gravity. Oil-impregnated surfaces bring additional complexity since both the droplet and the underlying oil film deform during impact. In this study, we experimentally characterize and model droplet impact, spreading, retraction, ejection, and the instability-induced breakup and splashing mechanism of the radially expanding liquid lamella when a millimeter size droplet impinges on a thin lubricant film. Our preliminary results of high-velocity droplet impact show that the density and viscosity ratios between the droplet and the lubricant film play a pivotal role in the outcome of the droplet impact. The insights gained from this work advance our understanding of the fundamental physics that govern droplet-surface interaction during impact.