Fluid mechanics of grab/release and volume scavenging instabilities:

生态旅游- 0653831 p。H. Steen， Cornell University - endowed液/气界面的表面张力被认为是内聚的，在小尺度上，液体的毛细作用在相邻的固体之间产生吸引力。棕榈甲虫表现出的超粘附是基于毛细管的。它的抓取和释放能力取决于操纵大量N小体积液体的表面张力。这项释放流体力学研究的重点是当两个或多个毛细表面（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依据——通过实验实现受甲虫启发的人造粘垫——并更好地了解甲虫的非凡能力。知识价值。通常微弱的表面张力可以通过平行作用有效地放大。棕榈甲虫，一种原产于佛罗里达的昆虫，表现出非凡的附着力（“超级附着力”），作为一种利用这种策略的防御机制。它的粘性来自于与12万个微小的油滴接触。这些小小的液体桥连接在一起，可以承受甲虫体重100倍的力。也许，最令人惊讶的是，这种联系可以在不到一秒钟的时间内释放。甲虫是如何释放自己的？如果液体桥之间的体积交换是可能的，一个桥可以清除邻近的体积。这种不稳定是什么时候发生的，如果发生了，它能缓解脱离吗？清除是否可以在人造装置中避免或增强？本文旨在回答这些问题。它们属于对N个耦合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，当清除与分离时间尺度竞争时，体积传递的动力学是重要的。更广泛的影响。大自然提供了多种可控粘附的例子（家蝇、壁虎等）。这种甲虫的特点是它能控制百升体积的液体油。了解甲虫的释放机制不仅对博物学家很重要，而且对工程师也很重要。拟议的研究解决了人造粘合剂的可行性，即单位重量的强度与甲虫所展示的强度相当，并且可以在一秒钟内打开/关闭（抓住/释放）。因此，直接的影响将是人类为广泛的应用（悬挂天花板的机器人设备等）制造可切换的超级粘合剂垫的能力。更广泛地说，人们普遍认为两个固体之间的粘附和在液-固界面上的扩散与固体液体涂层中运动部件之间的摩擦和耗散问题密切相关。更高效的涂层工艺将影响工业生产和日常人类活动。最高水平的影响将是对理解n耦合毛细管元件系统稳定性的科学基础的影响。最后，通过对学生的教育以及对公众的宣传，这项研究将产生影响。大众媒体对自然启发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.