Investigation of dynamics of a droplet impacting a pair of circular cylinders

Abstract

This study explores the intricate dynamics of droplet impact on adjacent cylindrical surfaces. Utilizing the multiphase lattice Boltzmann method and the Allen-Cahn equation, the research delves into how various factors such as droplet size, velocity, surface wettability, and cylinder proximity influence the impact dynamics. It is found that increasing the distance between the cylinders enhances the penetration of the liquid phase and the maximum extent of the liquid ligament. As the distance between the cylinders increases from six to 20 lattice points, the length of the liquid ligament increases from one time the droplet radius to four times the droplet radius. The study also examines the impact of Reynolds and Weber numbers on droplet dynamics. A reduction in the Reynolds number diminishes the impact inertia, leading to a decrease in the initial length of the liquid ligament and the wetted surface area. Over time, however, the final length of the liquid between the cylinders and the wetted surface is higher for lower Reynolds number impacts due to less liquid separation from the cylinder surfaces. An increase in the Weber number, conversely, reduces surface tension effects relative to inertial force, causing more extensive spreading of the droplet on the cylinder surfaces and altering the movement of separated droplets postimpact. Furthermore, the study highlights the influence of surface wettability. As the contact angle increases, hydrophobic effects repel the liquid phase, resulting in more elongated droplets postimpact. The length of the liquid ligament has increased from 2.5 times the droplet radius at a 30°contact angle to four times the droplet radius at a 150°contact angle. At lower contact angles, the predominance of surface adhesion facilitates quicker equilibrium attainment, while higher contact angles lead to prolonged equilibrium due to oscillatory droplet behavior. These findings offer novel insights into the interactions between droplets and adjacent curved surfaces, with significant implications for optimizing industrial processes and developing new technologies in fields such as inkjet printing and spray coating.