Droplets impact on rotating cylinders

In the present work, the impact dynamics of oil droplets on curved surfaces is reported. The influences of curvature, surface roughness, rotating speed, and wetting conditions on the impact dynamics are investigated. It is found that the deformation of droplets on rotating cylinders is more significant than that on static ones. An interesting bouncing phenomenon on rotating, pre-wetted, and curved surfaces is reported, and bouncing dynamics under different conditions are highlighted. Numerical simulation indicates that the sunken of liquid film on the cylinder surface generates a liquid camber there and seals compressed air, providing a cushion effect for droplets bouncing. Critical conditions are given to identify the velocity thresholds of droplets bouncing and depositing. This work provides a basic understanding of droplets impact dynamics on curved surfaces and design concepts for applications in modern industry, such as mist lubrication systems.