CAREER: From Single Swimmers to Swarms: A Computational Study of Mesoscale Active Matter In Fluids

职业：从单个游泳者到群体：流体中中尺度活性物质的计算研究

• 批准号: 1753148
• 负责人: Daphne Klotsa
• 金额: $ 50万
• 依托单位: University of North Carolina at Chapel Hill
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2018
• 资助国家: 美国
• 起止时间: 2018-03-01 至 2025-02-28
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1753148&HistoricalAwards=false
• 关键词: CAREER; Single; Swimmers; Swarms; Computational

NONTECHNICAL SUMMARYThis CAREER award supports theoretical and computational research integrated with education on active matter, an area of soft matter inspired by biology that focuses on understanding soft matter made from fundamental building blocks that are maintained far from the steady state of equilibrium by injecting energy at microscopic scales. It takes a trip to the local aquarium for one to admire schools of small fish forming spectacular patterns as they swim and swirl in a coherent synchronous manner. The tiniest jolt from an intruder, a big fish perhaps, sends the school into a momentary frenzy, where the little creatures explode in all directions, only to reform the swarm seconds later. Squint a little and the school of fish appears like one object, one continuous "living" material with a life and intelligence of its own; grander than the sum of its parts, smarter than the individual organisms. The dynamic properties of such "living materials" contrast sharply with the static characteristics of traditional materials. The former consists of "active" components such as bacteria, self-propelled nanorods, or molecular motors, that locally consume energy to move, exert forces or perform chemical reactions, and so, are inherently out of equilibrium, while the latter have fundamental building blocks that are "passive", such as molecules at equilibrium. The PI envisions designing a new and distinct class of materials by putting together active components to create active materials. In the same way that schools of fish respond to predators, swarms of bacteria swim towards nutrients, or skin heals itself when wounded, an artificial active material of self-propelled colloids or insect drones can respond to stimuli, restore coherence of the flock or "self-heal", adapt, store energy and information, assemble and disassemble at will. The PI aims to formulate a framework for understanding active matter based on statistical physics which focuses on systems composed of a large number of particles that will contribute to the foundations for developing design rules for making living materials with functionality beyond ordinary materials. Applications with broad societal impact range from novel active materials that are responsive, adaptive and self-healing, to aquatic swarming robots, for example for ocean exploration, under-water maintenance, remediation of oil, detection and collection of plastics in the ocean, to novel drug delivery platforms. The research and education plans are tightly integrated to one another, and both are designed to incorporate diversity. The PI will collaborate with programs that promote and advise on diversity, as well as evaluate success, and will include minorities and underrepresented groups both in her group and through outreach. Undergraduate and graduate students and postdoctoral fellows will receive training in a highly interdisciplinary field that combines computational, and analytical skills and draws knowledge from materials, physics, chemistry, biology, mathematics and engineering. Broader outreach with the public will be achieved through three exciting avenues: (i) podcast interviews; (ii) online material and a blog for students and postdocs with children; (iii) soft matter video project and (iv) local community outreach at science fairs. TECHNICAL SUMMARY This CAREER award supports theoretical and computational research integrated with education on active matter under conditions of intermediate Reynolds number flow. The complexity of emergent active-matter behavior has been demonstrated at many length-scales in both biological and artificial systems. Most studies so far have either developed minimal models without hydrodynamic interactions or focused on microscopic scales, where the Reynolds number approaches zero, Stokes flow. Both approaches are vibrant fields of research showing novel emergent behavior and providing insight for nonequilibrium theories of active matter. However, a whole region of parameter space. active matter of inertial particles at intermediate Reynolds numbers, remains largely unexplored. The intermediate regime covers at least three orders of magnitude in the Reynolds number and opens numerous possibilities for materials science, and describing millions of different organisms that one can study as model systems. The overarching goal of this project is to study active particles in fluids where viscous and inertial forces coexist with the aim to build a framework for describing mesoscale active matter suspensions. The two main thrusts that build upon each other towards that goal are to: (1) study and classify single model swimmers, at the point they transition from low to intermediate Reynolds numbers, and then for increasing Reynolds numbers; (2) examine the pairwise interactions for different model swimmers and establish an understanding of their collective behavior, emergent swarming and many-body interactions. In this way, the research will contribute to formulating a statistical mechanics based framework of active inertial suspensions.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

非技术总结这个职业奖项支持与活性物质教育相结合的理论和计算研究，活性物质是一个受生物学启发的软物质领域，专注于理解由基本构建块组成的软物质，这些构建块通过在微观尺度上注入能量来保持远离稳定状态的平衡。要欣赏成群的小鱼，你需要去当地的水族馆一游，它们以连贯的同步方式游泳和漩涡，形成壮观的图案。入侵者--也许是一条大鱼--最微小的震动，就会让整个鱼群陷入短暂的疯狂之中，小生物向四面八方爆炸，几秒钟后才改变了鱼群。稍微眯一眼，鱼群就像一个物体，一个连续的具有生命和智慧的“活”物质；比它的各个部分的总和更宏大，比单个有机体更聪明。这种“活材料”的动态特性与传统材料的静态特性形成鲜明对比。前者由细菌、自行式纳米棒或分子马达等“主动”组件组成，这些组件在局部消耗能量来移动、施力或进行化学反应，因此，它们天生就是不平衡的，而后者则有基本的“被动”构件，如处于平衡状态的分子。PI设想通过将活性成分组合在一起来创建活性材料来设计一种新的、独特的材料类别。就像鱼群对捕食者做出反应，细菌群游向营养物质，或者皮肤在受伤时自我愈合一样，一种由自我推进的胶体或昆虫无人机组成的人造活性材料可以对刺激做出反应，恢复群体的连贯性或“自我修复”，适应、储存能量和信息，随意组装和拆卸。PI旨在建立一个基于统计物理的理解活性物质的框架，该框架侧重于由大量粒子组成的系统，这将有助于制定设计规则，使生物材料具有超出普通材料的功能。具有广泛社会影响的应用范围从响应性、适应性和自愈性的新型活性材料到水上成群的机器人，例如用于海洋勘探、水下维护、修复石油、检测和收集海洋中的塑料，以及新型药物输送平台。研究和教育计划紧密结合在一起，两者的设计都包含了多样性。PI将与促进多样性和就多样性提供建议的项目合作，并评估成功，并将少数族裔和代表性不足的群体包括在她的团队中和通过外联。本科生、研究生和博士后研究员将接受高度跨学科领域的培训，该领域结合了计算和分析技能，并吸取了材料、物理、化学、生物、数学和工程方面的知识。将通过三种令人兴奋的途径扩大与公众的联系：(I)播客访谈；(Ii)为学生和儿童博士后提供在线材料和博客；(Iii)软物质视频项目；以及(Iv)在科学博览会上向当地社区宣传。技术总结该职业奖支持在中雷诺数流条件下与活性物质教育相结合的理论和计算研究。在生物和人工系统中，涌现的活性物质行为的复杂性已经在许多长度尺度上被证明。到目前为止，大多数研究要么建立了没有流体动力相互作用的最小模型，要么集中在雷诺数接近于零的微观尺度上，即斯托克斯流。这两种方法都是充满活力的研究领域，展示了新的涌现行为，并为活性物质的非平衡理论提供了洞察力。然而，参数空间的整个区域。处于中间雷诺数的惯性粒子的活性物质，在很大程度上仍未被探索。中间体系至少涵盖雷诺数的三个数量级，并为材料科学开辟了无数可能性，并描述了数百万种不同的生物体，人们可以将其作为模型系统进行研究。该项目的总体目标是研究粘性和惯性力共存的流体中的活性粒子，目的是建立一个描述中尺度活性物质悬浮液的框架。为了实现这一目标，相互促进的两个主要努力是：(1)研究和分类单一模型游泳者，在这一点上，他们从低雷诺数过渡到中雷诺数，然后增加雷诺数；(2)检查不同模型游泳者的成对相互作用，并建立对他们的集体行为、新出现的群体和多体相互作用的理解。通过这种方式，这项研究将有助于建立一个基于统计力学的主动惯性暂停框架。这一奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

项目成果

Reciprocal swimming at intermediate Reynolds number

中间雷诺数的往复游泳

• DOI: 10.1017/jfm.2022.873
• 发表时间: 2022
• 期刊: Journal of Fluid Mechanics
• 影响因子: 3.7
• 作者: Derr, Nicholas J.;Dombrowski, Thomas;Rycroft, Chris H.;Klotsa, Daphne
• 通讯作者: Klotsa, Daphne

Pairwise interactions between model swimmers at intermediate Reynolds numbers

模型游泳者之间在中间雷诺数下的成对相互作用

• DOI: 10.1103/physrevfluids.7.074401
• 发表时间: 2022
• 期刊: Physical Review Fluids
• 影响因子: 2.7
• 作者: Dombrowski, Thomas;Nguyen, Hong;Klotsa, Daphne
• 通讯作者: Klotsa, Daphne