Cavity and jet formation after immiscible droplet impact into deep water pool

Abstract

The impact behavior of a droplet in a liquid pool is of fundamental importance in nature and industrial applications. While there are several reports on using the same fluid type for the droplet and liquid pool, there are a few reports on the use of different liquids. Moreover, the mixing process of the droplet and liquid pool is yet to be fully quantified. Herein, we present an experimental setup to study the effect of droplet solubility in water on the impact characteristics of a deep-water pool. In this study, we used three droplets (water, ethanol, and silicone oil) with different densities, surface tensions, viscosities, and solubilities in water and visualized the impact process using a high-speed camera. The diameter of the droplets ranged from 2.0 to 3.4 mm, and the impact velocities ranged from 1.4 to 3.2 m/s. The depth of the droplet pool was fixed at 30 mm. To better understand the impact characteristics, the obtained images were processed to quantify the created cavity and the subsequent liquid jet formed by the droplet impact. Energy analysis performed during the droplet impact process for the 1000 cSt silicone oil droplet revealed that approximately 70% of the impact energy was converted into cavity energy, and the remaining 30% was converted into flow loss. These experimental results provide physical insight into the immiscibility effect on droplet impact dynamics in a deep pool and pave the way for practical applications.