论文标题
用无柄滴扫聚
Sweeping by Sessile Drop Coalescence
论文作者
论文摘要
在液体液滴合并的过程中，接触固体，液体扫过润湿和固体投射的区域。扫地的程度决定了设备的性能，例如自我清洁表面，反弗罗斯特涂料，收割机和掉落的冷凝器。对于这些应用，由于增强滴动力学行为，因此优选弱和非润湿固体底物。因此，我们这里的合并研究仅限于触点角度90°$ \leθ_{0} \ le $ 180°。二元连钉滴融化是重点，将流体模拟的数量用作主要工具。结合了基斯特勒动态接触角模型的仿真首先是针对三个不同的实验底物系统验证的，然后用来通过修改$θ_{0} $来研究固体润湿性对清除的影响。随着$θ_{0} $的增加，随着质量下降中心的增长，润湿和投射的扫掠区域都会增加。对于$θ_{0} \ ge $ 150°，由于底物的润湿性降低以及由于破坏对称性的固体而引起的液体动量的焦点，因此发生合并引起的下降跳跃。在这个制度中，预计的扫荡区域继续随$θ_0$增加而增加，而湿扫地则达到最大值，然后减小。使用流体动力学理论的机械能平衡来解释全面的结果，并与游离滴相结合进行了比较。
During coalescence of liquid drops contacting a solid, the liquid sweeps wetted and solid-projected areas. The extent of sweeping dictates the performance of devices such as self-cleaning surfaces, anti-frost coatings, water harvesters, and dropwise condensers. For these applications, weakly- and non-wetting solid substrates are preferred as they enhance drop dynamical behavior. Accordingly, our coalescence studies here are restricted to drops with contact angle 90° $\le θ_{0} \le$ 180°. Binary sessile drop coalescence is the focus, with volume of fluid simulations employed as the primary tool. The simulations, which incorporate a Kistler dynamic contact angle model, are first validated against three different experimental substrate systems and then used to study the influence of solid wettability on sweeping by modifying $θ_{0}$. With increasing $θ_{0}$ up to 150°, wetted and projected swept areas both increase as drop center of mass heightens. For $θ_{0} \ge$ 150°, coalescence-induced drop jumping occurs owing to the decreasing wettability of the substrate and a focusing of liquid momentum due to the symmetry-breaking solid. In this regime, projected swept area continues to increase with $θ_0$ while wetted swept area reaches a maximum and then decreases. The sweeping results are interpreted using the mechanical energy balance from hydrodynamic theory and also compared to free drop coalescence.
