Behaviors of a Droplet Impact on a Cylinder

Abstract

The hydrodynamic behaviors of a droplet impacting a cylindrical surface were experimentally investigated, examining the effects of cylinder-to-droplet diameter ratio (d*), impact velocity (v0), contact angle (θ), and relative eccentric distance (e*). Temporal evolutions of droplet behavior in the circumferential and axial directions were captured using a high-speed camera. Results indicate that the spreading process can be categorized into four stages based on contact line movements: impact, spreading, oscillation, and stabilization. The rebound height after impact decreases progressively with decreasing d* and increasing Weber number (We). The maximum spreading length increases with droplet diameter and Weber number, while a lower contact angle also contributes to a greater maximum spreading length. For eccentric impacts, the effects of circumferential asymmetry and surface hydrophilicity on spreading become more pronounced with larger e*. Additionally, a novel correlation was developed to predict the maximum spreading lengths of the droplet in the circumferential and axial directions for central impacts.