Minimal addition of fumed nanoparticles suppresses droplet splashing

Abstract

Droplet splashing is a common issue in various applications, from industrial processes to natural phenomena. This study demonstrates a method for suppressing droplet splashing by adding minute concentrations (as low as 0.1 wt. %) of fumed silica, titania, alumina, or magnesia nanoparticles to glycerol–water mixtures. Surprisingly, the suppression is more effective at higher impact velocities, where splashing is typically more severe. Our high-speed imaging and rheological measurements reveal that this effect arises from the emergence of elasticity in the nanofluids at extreme shear rates. This emergent elasticity, due to particle agglomeration and network formation, is demonstrated in the dilute fumed metal oxide nanofluids. Based on our findings, we propose a splashing threshold applicable to all liquids, including the non-Newtonian nanofluids studied here. This threshold is validated using Drop Impact Viscometry to accurately measure viscosity at high shear rates. These results offer an approach to designing splash-resistant liquids with minimally altered bulk properties.