Aerosol generation from liquid droplet impact on solid surfaces

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Liquid jets are widely encountered from printing to 'big industry' which use jets for a range of applications including decontaminating surfaces (buildings, reactors etc.). In most applications Rayleigh instability of the liquid jet promotes breakup of the jet into sub-millimetre droplets which then impact on the solid surface resulting in either droplet spreading, rebounding or breakup. The outcome of a droplet impacting on a solid surface is dependent on the surface (wettability, roughness) and fluid (viscosity, surface tension) properties, and the droplet impact velocity. An undesirable effect in most applications is droplet splashing and the formation of micron-sized aerosol droplets which become mobile and contaminate the surrounding environment. We will study the generation of aerosol droplets (droplet size and number) from single, millimetre-sized droplets impacting on a solid surface. Generation and mobility of the aerosol droplets will be investigated as a function of the fluid viscosity (chemical additives), interfacial rheology, and velocity of an air flow perpendicular to the droplet trajectory. Routes to minimize aerosol generation while maintaining high impact velocities will be explored. The project will include both experimental and computational research.