Alam M D Erfanul, Kauffman Jeffrey L, Dickerson Andrew K
Department of Mechanical and Aerospace Engineering, University of Central Florida, USA.
Soft Matter. 2020 Feb 19;16(7):1931-1940. doi: 10.1039/c9sm02253h.
The task of moisture removal from small, delicate surfaces such as sensors and flight surfaces on micro-flyers can be challenging due to remote location and small scale. Robustness is enhanced when such surfaces, of comparable scale to deposited drops, can remove deposition without external influence. At this scale, the dynamics of a solid surface responding to a mechanical input is highly-coupled to the fluid resting above. In this study, we explore highly-coupled fluid-solid mechanics using singular liquid drops of water and a glycerin solution resting on millimetric, forced cantilevers. These wing-inspired cantilevers are sinusoidally displaced at their base across 85-115 Hz, producing surface accelerations up to 45 gravities at drop release. We observe three principal drop release modes: sliding, normal-to-cantilever ejection, and drop pinch-off. Release modes are dependent on drop and cantilever properties, and cantilever motion. Predictions of ejection modes are accomplished by application of Euler elastica theory and drop adhesion forces. Lastly, we determine damping of cantilever motion imposed by sloshing drops.
从诸如微型飞行器上的传感器和飞行表面等小而精密的表面去除水分的任务可能具有挑战性，因为其位置偏远且规模小。当这些与沉积液滴规模相当的表面能够在无外部影响的情况下去除沉积物时，其坚固性会增强。在这个尺度下，固体表面对机械输入的响应动力学与上方静止的流体高度耦合。在本研究中，我们使用放置在毫米级受迫悬臂梁上的奇异水滴和甘油溶液来探索高度耦合的流固力学。这些受机翼启发的悬臂梁在其基部以85 - 115赫兹的频率作正弦位移，在液滴释放时产生高达45倍重力加速度的表面加速度。我们观察到三种主要的液滴释放模式：滑动、垂直于悬臂梁弹出和液滴夹断。释放模式取决于液滴和悬臂梁的特性以及悬臂梁的运动。通过应用欧拉弹性理论和液滴附着力来预测弹出模式。最后，我们确定晃动液滴对悬臂梁运动的阻尼作用。
