In this work, the coalescence of two equal‐sized water droplets on superhydrophobic surfaces (SHSs) is experimentally investigated. The morphologies of droplet coalescence are observed from side‐view and bottom‐view using high‐speed camera system. The related morphology evolution and dynamics of droplet coalescence are explored. The dynamic behaviors of droplet coalescence on SHSs can be decomposed into liquid bridge growth, contact line evolution, and droplet jumping. The liquid bridge radius is proportional to the square root of time, whereas the dimensionless prefactor is decreased from 1.18 to 0.83 due to the transition of interface curvature. The retraction velocity of the contact line shows limited dependence on initial droplet radii as the retraction dynamics considered here are governed by the capillary–inertial effect. The coalesced droplet finally departs the substrate with a dimensionless jumping velocity of around 0.2. A heuristic argument is made to account for the nearly constant dimensionless jumping velocity. © 2018 American Institute of Chemical Engineers AIChE J, 64: 2913–2921, 2018

中文翻译：

---

超疏水表面上液滴聚结的形态演化和动力学

在这项工作中，实验研究了两个相同大小的水滴在超疏水表面（SHS）上的聚结。使用高速相机系统从侧面和底部观察液滴的聚结形态。探索了液滴聚结的相关形态演化和动力学。SHS上液滴聚结的动力学行为可以分解为液桥生长，接触线演变和液滴跳跃。液桥半径与时间的平方根成比例，而无因次系数因界面曲率的过渡而从1.18降低至0.83。接触线的回缩速度对初始液滴半径的依赖性有限，因为此处考虑的回缩动力学受毛细惯性作用控制。聚结的液滴最终以约0.2的无因次跳跃速度离开基板。试探性地解释了几乎恒定的无量纲跳跃速度。©2018美国化学工程师学会AIChE J，64：2913–2921，2018