Simulation of Droplet Impact on a Spherical Surface

Droplet impact phenomenon is widely found in nature, production and life. Due to the complexity of the actual surface structures, the droplet may impact not only on a flat surface but also on surfaces of various shapes and the one typical example is a sphere. In this study, the droplet impact process on a spherical surface is simulated using the VOF multiphase model coupled the dynamic contact angle model, which is compared with our experimental data to verify the model. Based on this model, the impact processes of droplets with different We numbers on spherical surfaces with different diameters and contact angles are simulated. The results indicate that the maximum spreading factor increases significantly with the increase of We and the decrease of contact angle while it is little influenced by the sphere diameter. The droplet may break up at the spreading or receding stage during the whole impact process. Compared with impacting on the flat surface, the droplet is more likely to break up when impacting on a sphere due to the gravity and the critical We number for breaking up is smaller. The droplet breaking-up diagram is obtained, which provides reference for the droplet impact study.