Droplet splashing during the impact on liquid pools of shear-thinning fluids with yield stress

TL;DR

This study investigates how shear-thinning fluids with yield stress influence droplet splashing dynamics through experiments and simulations, revealing significant effects of non-Newtonian properties on ejecta sheet formation and propagation.

Contribution

It provides new insights into droplet impact behavior of non-Newtonian fluids, focusing on shear-thinning fluids with yield stress, which has been less explored compared to Newtonian fluids.

Findings

Ejecta sheet formation is easier with lower flow index.

Large yield stress affects ejecta sheet thickness.

Inertia dominates ejecta sheet propagation, aligning spreading radius with geometrical radius.

Abstract

The impact of droplets on liquid pools is ubiquitous in nature and many industrial applications. Most previous studies of droplet impact focus on Newtonian fluids, while less attention has been paid to the impact dynamics of non-Newtonian droplets, even though non-Newtonian fluids are widely used in many applications. In this study, the splashing dynamics of shear-thinning droplets with yield stress are studied by combined experiments and simulations. The formation and the propagation of the ejecta sheet produced during the splashing process are considered, and the velocity, the radius, and the time of the ejecta sheet emergence are analyzed. The results show that the non-Newtonian fluid properties significantly affect the splashing process. The ejecta sheet of the splashing becomes easier to form as the flow index reduces, the large yield stress can affect the thickness of the ejecta sheet, and the spreading radius collapses into a geometrical radius due to that the inertia force is the dominant factor in the ejecta sheet propagation.