Maximum spreading of an impact droplet on a conical tip

The droplet impact process on a conical tip is one of the key problems in the field of fluid mechanics and surface and interface science. This study examines the impact process of water droplets on the conical tip using experimental, numerical, and theoretical approaches. The volume of fluid method and the dynamic contact angle model are used and validated by comparing the numerical and experimental results in both the present work and literature. The effects of the Weber number, contact angle, and cone angle on the droplet behavior, especially the maximum spreading factor, are investigated. The findings indicate that the maximum spreading factor becomes larger at a larger Weber number, a smaller contact angle, and a cone angle. Based on energy conservation, two theoretical models considering the film and ring profiles are proposed to describe the droplet maximum spreading factor. The film and ring models are recommended for use when the maximum spreading factor is below and above 2.4, with the relative deviation of all calculated data less than ±18%. This study enhances the understanding of droplet impacts on complex surfaces and provides valuable guidance for engineering applications.