EAGER: Emergent order of hydrodynamically coupled microrotors

EAGER：流体动力耦合微转子的涌现顺序

• 批准号: 1544196
• 负责人: Petia Vlahovska
• 金额: $ 10万
• 依托单位: Brown University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2015
• 资助国家: 美国
• 起止时间: 2015-09-01 至 2016-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1544196&HistoricalAwards=false
• 关键词: EAGER; Emergent; order; hydrodynamically; coupled; EAGER; Emergent; order; hydrodynamically; coupled

1544196(Vlahovska)The objective of the proposed research is to investigate theoretically and experimentally a new class of active fluids, that of suspensions of self-rotating particles. Active fluids are fluids that behave in unique ways, because of the presence of active particles that can self-assemble, or can move and pack in different ways, giving different macroscopic properties to the fluid. Certain complex fluids and biofluids fall in this category. Even a flock of birds, or a school of fish, where each moving animal moves on its own, but the motion of all follows a pattern at a much larger scale than the individual, are examples of active fluids.It is proposed to examine dense suspensions of rotating spheres (rotors). It has very recently been found that in a monolayer of rotors with initially randomly distributed up or down spins, same-spin rotors spontaneously segregate and collectively move in traffic lanes or circulate in large vortices. When the rotor density gets close to maximum packing, the rotors jam into crystals that continuously melt, reassemble, and move. It is proposed to study these phenomena with a combined computational and experimental approach to understand how this collective behavior emerges from the hydrodynamic interactions between the rotors. The numerical simulations are based on the immersed boundary method. The experimental system relies on the Quincke effect, which is the spontaneous spinning of a dielectric sphere in an applied uniform electric field. The proposed research aims to (1) include the electrostatic interactions in the numerical simulations, and (2) investigate the dynamics of a pair and monolayer of Quincke rotors. In addition to advancing basic knowledge, the research will uncover novel dynamic structures that could be exploited for design of `smart' materials responsive to the external environment. The PIs will incorporate the results from this research in graduate courses and will also leverage successful outreach programs at Brown University to communicate the relevance and significance of the work to the general public.

1544196（Vlahovska）提出的研究的目的是在理论和实验上研究一类新的活性流体，即自动旋转颗粒的悬浮液。活性流体是以独特方式行为的流体，因为存在可以自组装或可以以不同方式移动和包装的活性颗粒，从而为流体提供了不同的宏观特性。某些复杂的流体和生物流体属于这一类别。即使是一群动物自行移动的鸟类或一群鱼学校，但所有动物的运动都比个人大得多。最近发现，在最初随机分布的转子单层中，相同的旋转转子自发地分离并集体在交通车道中移动或以大型涡流循环。当转子密度接近最大填料时，转子塞入晶体中，不断融化，重新组装和移动。有人提出使用合并的计算和实验方法研究这些现象，以了解这种集体行为是如何从转子之间的流体动力相互作用中出现的。数值模拟基于浸没的边界方法。实验系统依赖于Quincke效应，Quincke效应是在应用均匀电场中介电球的自发旋转。拟议的研究目的是（1）包括数值模拟中的静电相互作用，（2）研究Quincke转子的一对和单层的动力学。除了促进基本知识外，该研究还将发现可利用的新型动态结构，这些结构可以用于设计响应外部环境的“智能”材料的设计。 PI将在研究生课程中纳入这项研究的结果，还将利用布朗大学成功的外展计划来传达与公众的相关性和意义。