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

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.

Fluid properties:
The non-Newtonian fluid used in this study is 0.05 wt% Carbopol solution (Carbopol 940 supplied by Lubrizol), prepared using the same method as Luu and Forterre40 . First, Carbopol powder was slowly added into deionized (DI) water at 50 ◦C, and continuously stirred at 500 rpm for several hours. Then, a sodium hydroxide solution of 18 wt% was added into the solution to bring the pH from U0 PC with image acquisition software Syringe pump Droplet LED Lamp Liquid pool High-speed camera FIG. 1. Schematic diagram of the experimental setup for the impact of droplets on liquid pools. 3 up to 7. After that, the solution was adequately mixed at 700 rpm until no bubbles and lumps in the transparent gel.

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Article information: Xiaoyun Peng and Tianyou Wang and Kai Sun and Zhizhao Che. Droplet splashing during the impact on liquid pools of shear-thinning fluids with yield stress. 2110.09328. arXiv, 2021.