Axisymmetric Ellipsoidal Droplet Impact on a Horizontal Solid Surface

Droplet impact process on a solid surface exists in fields such as coating chemistry, inkjet printing, aerospace, etc. In many cases, the initial shape before a droplet impacts on the surface will be effected by the surroundings including flow, gravity and electric field and so on. Thus, a droplet with irregular initial shape will have a quite different impact process from a spherical droplet. In this work, the impact processes of spherical droplets are first simulated using VOF multiphase model coupled with Kistler's dynamic contact angle model, which is verified by the results in our experiment and reference. Then, simulations are conducted on the impact processes of axisymmetric ellipsoidal droplets with different aspect ratios (0.5~2.0) under serials of contact angle (30°~150°) and We number (10~90). It is found that the maximum spreading factor and its corresponding time increases with increases of We number and aspect ratio and decrease of contact angle. Based on an approximate theoretical analysis, an correlation between the maximum spreading factor and We number, contact angle and aspect ratio is proposed, aimed to improve the understanding of the mechanism of droplet impact.