Fluid mechanics of grab/release and volume scavenging instabilities:

CBET-0653831P。H·斯蒂恩，康奈尔大学-Endowed已知液/气界面上的表面张力具有内聚性，小尺度上的液体毛细作用在相邻固体之间产生吸引力。棕榈虫表现出的超强粘附性是基于毛细管的。它的抓取和释放能力取决于操纵大量N的小体积液体，这些液体由表面张力持有。这项释放流体力学的研究重点放在两个或更多毛细表面(例如液滴)连接时可能发生的体积清除不稳定性，从而实现体积交换。建模和计算将为目标任务提供科学基础--在实验上实现受甲虫启发的人造粘合垫--并更好地了解甲虫的非凡能力。智力上的优点。平行力可以有效地放大通常较弱的表面张力。棕榈甲虫是一种原产于佛罗里达州的昆虫，仅使用这种策略就表现出超乎寻常的粘附性(超级粘附性)作为一种防御机制。它的粘性来自于与12万个微小的油滴接触。这些微小的液体桥合在一起形成了一种纽带，可以承受高达甲虫体重100倍的力。也许，最令人惊讶的是，这种债券可以在不到一秒的时间内释放。甲虫是如何自我释放的？如果液体桥之间的体积交换是可能的，一个桥可以从它的邻居那里收集体积。这种不稳定是什么时候发生的，如果真的发生了，它能缓解超然吗？在人造设备中可以避免或增强拾取吗？建议回答这些问题。它们属于对N个耦合的非线性液体组分系统稳定性的研究。静力学给出了能量格局，当拾取与支队的时间尺度竞争时，体积转移的动态是重要的。大自然提供了各种可控的粘附性例子(家蝇、壁虎等)。甲虫的独特之处在于它能控制皮升体积的液体油。了解甲虫的释放机制(S)不仅对博物学家，而且对工程师都很重要。这项拟议的研究涉及人造粘合剂的可行性，其单位重量的强度与甲虫展示的相当，并且可以在一秒钟内打开/关闭(抓取/释放)。因此，直接的影响将是人类为广泛的应用(天花板悬挂机器人设备等)制造可切换的超粘性衬垫的能力。更广泛地说，人们普遍认为，两个固体之间的粘合和在液-固界面上的扩散与运动部件之间的摩擦和固体液体涂层中的耗散密切相关。更有效的涂层工艺将对工业生产和日常人类活动产生影响。最高水平的影响将是对了解N-耦合毛细管元件系统稳定性的科学基础。最后，这项研究将通过教育学生产生影响，并扩大对公众的宣传。大众媒体对自然技术的大量报道引起了积极的共鸣，这是理所当然的。

CBET-0653831P. H. Steen, Cornell University - EndowedSurface tension at a liquid/gas interface is known to be cohesive and liquid capillarity at small scales exerts an attraction between adjacent solids. The super-adhesion exhibited by the palm beetle is capillarity-based. Its ability to grab and release depends on manipulating a large number N of small volumes of liquid held by surface tension. This study of the fluid mechanics of release has a focus on the volume-scavenging instabilities that can occur when two or more capillary surfaces (e.g. droplets) connect, enabling volume exchange. Modeling and computation will provide the scientific basis for the target task -- to experimentally realize a man-made adhesive pad inspired by the beetle -- and to better understand the beetle's remarkable capability. Intellectual merit. The normally weak force of surface tension can be effectively amplified by parallel action. The palm beetle, an insect native to Florida, exhibits extra-ordinary adhesion ('super-adhesion') as a defense mechanism using just this strategy. Its stickiness derives from making contact with 120,000 tiny droplets of oil. Together, these little liquid bridges make a bond that can withstand a force up to 100 times the beetle's body weight. Perhaps, most surprisingly, this bond can be released in less than a second. How does the beetle release itself? Provided volume exchange between liquid bridges is possible, one bridge can scavenge volume from its neighbors. When does this instability occur and, if it does occur, can it ease detachment? Can scavenging be avoided or enhanced in a man-made device? It is proposed to answer these questions. They belong to a study of the stability of a system of N coupled nonlinear liquid components. Statics gives the energy landscape and the dynamics of volume transfer is important when scavenging competes with the detachment time-scale.Broader Impacts. Nature provides a variety of controllable adhesion examples (house-fly, gecko, etc). The beetle is distinguished by its control of pico-liter volumes of liquid oil. Understanding the beetle's mechanism(s) of release is (are) important not only to the naturalist but to the engineer. The feasibility of man-made adhesives, of strength per unit weight comparable to what the beetle exhibits and that can be turned on/off (grab/release) on the order of a second, is addressed by the proposed study. Hence, immediate impact will be on man's capability to build a switchable super-adhesive pad for a breadth of applications (ceiling-hanging robotic devices and so forth). More broadly, it is well-accepted that adhesion between two solids and spreading at a liquid-solid interface are closely related to the issue of friction between moving parts and dissipation in the liquid coating of solids. More efficient coating processes would impact both industrial production and daily human activities. The highest level impact will be on the science base for understanding the stability of systems of N-coupled capillary elements. Finally, an impact through education of students will accrue from the study, as well as outreach to the public. Numerous accounts of nature-inspired technology in the popular press strike a positive chord, as they should.