Coalescence-Induced Jumping of Multiple Condensate Droplets on Hierarchical Superhydrophobic Surfaces.
Coalescence-Induced Jumping of Multiple Condensate Droplets on Hierarchical Superhydrophobic Surfaces.
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DOI：
10.1038/srep18649
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发表时间：
2016-01-04
影响因子：
4.6
通讯作者：
Garimella SV
中科院分区：
文献类型：
--
作者：
Chen X;Patel RS;Weibel JA;Garimella SV
定量表征了聚结引起的冷凝液滴从具有分级微/纳米级粗糙度的超疏水表面的跳跃。实验观察表明，凝结水滴跳跃是由多个不同尺寸的水滴合并引起的，并且合并后的水滴轨迹通常偏离表面法线。开发了一种离焦深度图像处理技术来跟踪跳跃液滴的面外位移，从而精确测量液滴的尺寸和速度。结果表明，当两个液滴合并时，可以获得最高的跳跃速度。尽管聚结时释放了更大的潜在表面能，但随着聚结液滴数量的增加，跳跃速度逐渐降低。开发了一个考虑粘性耗散、表面粘附、线张力、初始液滴润湿状态以及聚结液滴的数量和尺寸的通用理论模型，以解释实验中观察到的液滴跳跃速度的趋势。
Coalescence-induced jumping of condensate droplets from a superhydrophobic surface with hierarchical micro/nanoscale roughness is quantitatively characterized. Experimental observations show that the condensate droplet jumping is induced by coalescence of multiple droplets of different sizes, and that the coalesced droplet trajectories typically deviate from the surface normal. A depth-from-defocus image processing technique is developed to track the out-of-plane displacement of the jumping droplets, so as to accurately measure the droplet size and velocity. The results demonstrate that the highest jumping velocity is achieved when two droplets coalesce. The jumping velocity decreases gradually with an increase in the number of coalescing droplets, despite the greater potential surface energy released upon coalescence. A general theoretical model that accounts for viscous dissipation, surface adhesion, line tension, the initial droplet wetting states, and the number and sizes of the coalescing droplets is developed to explain the trends of droplet jumping velocity observed in the experiments.