Numerical simulation for behavior of a droplet impacting onto a target spherical surface

The deposition behavior of a droplet impacting on a spherical surface during liquid-jet process was illustrated here. The deformation model of a single droplet depositing on the spherical surface substrate was established with the theory of volume of fluid (VOF). The kinetic, spreading, relaxation and wetting phases of the droplet movement were respectively demonstrated in detail. The dynamic behavior of a droplet on a spherical surface was simulated with Fluent (6.3 version) numerical analysis platform. The effects of impact velocity, curvature radius of spherical surface, surface tension and viscosity on the deposition behavior of a droplet were investigated. There were several conclusions could be drawn from simulation results. They were that with increase in the impact velocity of droplet, the maximum spreading diameter increases and the minimum spreading thickness reduces; both the maximum spreading diameter and the minimum spreading thickness increase with increase in the diameter of target ball; after the viscosity coefficient of experiment liquid is larger than a certain value, the maximum spreading diameter reduces and the minimum spreading thickness increases with incease in its viscosity coefficient; when the surface tension coefficient of the liquid droplet increases, the maximum spreading diameter reduces and the minimum spreading thickness increases; in the initial stage of droplet spreading, the spreading thickness decreases linearly with increase in the droplet impact velocity; in addition, when the impact speed of the droplet is too large, either liquid's surface tension coefficient or the target sphere diameter is too small, a local breakage occurs at the center of the droplet colliding with a spherical surface during the first recoiling stage.