Exploring Droplet Impact and Splashing on Surfactant-Laden Shallow Pools*

The interaction between droplets and shallow pools plays a crucial role in various fields, from inkjet printing to coating technologies. Understanding the impact and splashing dynamics of droplets on liquid films is of significant interest for both fundamental research and practical applications. This is particularly true in the presence of surfactants, which can be either naturally occurring, purposely added, or undesired contaminants. In this presentation, we study droplet impact on surfactant-laden shallow pools, endorsing the effects of surfactant-induced Marangoni stresses. We study these phenomena to unravel the intricate mechanisms governing droplet impact and splashing behaviour. Furthermore, we explore the influence of surfactant properties on the interfacial dynamics, including the surfactant-induced local reduction of surface tension and the adsorption/desorption of surfactant between the interface and the bulk. Our findings shed light on the complex interplay between droplets, shallow pools, and surfactants, paving the way for enhanced control and optimisation of various processes involving droplet impact and shallow pools.