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

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）拟议研究的目的是从理论上和实验上研究一类新型活性流体，即自旋转颗粒悬浮液。活性流体是由于存在可以自组装或可以以不同方式移动和堆积的活性颗粒而以独特方式表现的流体，从而赋予流体不同的宏观特性。某些复杂的液体和生物液体属于这一类。即使是一群鸟或一群鱼，其中每个移动的动物都独立移动，但所有动物的运动都遵循比个体大得多的规模的模式，都是活性流体的例子。建议检查旋转球体（转子）的密集悬浮液。最近发现，在最初随机分布的向上或向下旋转的单层转子中，相同旋转的转子会自发地分离并集体在车道上移动或在大漩涡中循环。当转子密度接近最大堆积时，转子会挤入晶体中，晶体不断熔化、重新组装和移动。建议通过计算和实验相结合的方法来研究这些现象，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。数值模拟基于浸入边界法。该实验系统依赖于昆克效应，即电介质球在施加的均匀电场中自发旋转。拟议的研究旨在（1）在数值模拟中包含静电相互作用，以及（2）研究一对和单层昆克转子的动力学。除了推进基础知识之外，该研究还将发现新颖的动态结构，可用于设计响应外部环境的“智能”材料。 PI 将把这项研究的结果纳入研究生课程，并将利用布朗大学成功的外展项目向公众传达这项工作的相关性和重要性。