Eccentric impact of a submillimeter sphere on droplet surface under electric field

The process of a submillimeter sphere eccentric impacting a single droplet under electric field is experimentally investigated by using high-speed micrographic techniques in this paper. The spheres are released at a fixed height to impact different positions of droplets. With the increase in electric field intensity, the impact behavior evolves from oscillation mode to submergence mode. The trajectory of the sphere deviates from the impact direction affected by the eccentric impact. Each mode can be divided into three stages: slamming, cavity developing, and reverting. In the slamming stage, the sphere is decelerated by hydrodynamic forces where the kinetic energy loss increases with the increase in Weber number We. Surface tension becomes the dominant force in the cavity developing stage due to the expanding cavity. The impact angle \(\alpha \) and We show little influence on the expanding speed; thereinto We has a significant effect on the limit diameter of the cavity. The cavity with different \(\alpha \) and We reaches a peak value near the critical state of the impact angle of 90 degrees. A scaling law is constructed to obtain the transitional boundary between the impact modes based on dimensional analysis and data rearrangement. The electric force is mainly used to accelerate the sphere in the gas phase and has little influence on the solid–liquid interaction behavior after contacting the droplet.