UNS: Collaborative Research: Dynamics of Active Particles in Anisotropic Fluids

1510949(Cordova) & 1508987（Abbott）拟议研究的目标是用实验和计算两种方法来研究复杂的各向异性活性流体的行为。活性流体是具有独特行为方式的流体，因为活性颗粒的存在可以自组装，或者可以以不同的方式移动和包装，从而赋予流体不同的宏观特性。提出的研究可以揭示新的现象，可以用于设计新的流体材料，对其外部环境作出反应。过去的研究主要集中在各向同性牛顿流体中“活性胶体”的物理性质上，然而，活性流体的许多未来应用将需要了解它们在复杂流体中的行为。这是本提案所涵盖的空白：流体粘弹性特性的各向异性如何影响涉及活性胶体的基本输运现象。第一个研究重点将集中在液晶悬浮液的各向异性环境对悬浮液中自推进粒子的扩散率的影响。具体来说，布朗动力学（BD）模拟将与跟踪向列液晶界面上单个自推进胶体Janus粒子的实验相结合。第二个重点将集中在各向异性流体中悬浮的主动粒子对被动示踪粒子扩散的影响。分散在生物相容性液晶中的活动细菌将用于探索在杆状细菌运动的存在下被动粒子如何扩散。这个综合实验和模拟程序的总体结果将是关于复杂流体中由内部产生的梯度驱动的基本输运过程的新知识。协作小组将与波多黎各马亚圭斯大学的教师培训方案建立合作，以发展、传播和评价双语教育模块。教育活动旨在让学生接触跨文化教育经验，并为他们在不同的环境中工作做好准备。两所学院的学生都将开设一门关于软物质的跨学科课程。

1510949(Cordova) & 1508987(Abbott)The goal of the proposed research is to investigate with both experiments and computations the behavior of complex, anisotropic active fluids. 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. The proposed research can uncover novel phenomena that could be exploited for design new fluid materials that are responsive to their external environment. Past studies have focused largely on the physics of "active colloids" in isotropic Newtonian fluids, yet many future applications of active fluids would require an understanding of their behavior in complex fluids. This is the white space that this proposal covers: how anisotropy in the viscoelastic properties of a fluid can impact fundamental transport phenomena involving active colloids. A first research thrust will focus on the effect of the anisotropic environment of a liquid crystal suspension has on the diffusivity of a self-propelled particle within the suspension. Specifically, Brownian Dynamics (BD) simulations will be combined with experiments involving tracking of single self-propelled colloidal Janus particles at the interface of a nematic liquid crystal. A second thrust will focus on the effects of a suspension of active particles hosted within an anisotropic fluid on the diffusion of passive tracer particles. Motile bacteria dispersed within biocompatible liquid crystals will be used to explore how passive particles diffuse in the presence of the motion of the rod-shaped bacteria. The overall outcome of this integrated program of experiment and simulation will be new knowledge regarding fundamental transport processes driven by internally generated gradients in complex fluids. The collaborating group will establish a collaboration with the Teacher Preparation Program at the University of Puerto Rico Mayaguez to develop, disseminate and assess bilingual educational modules. Educational activities are proposed to expose students to cross-cultural educational experiences and to prepare them to work in diverse settings. An interdisciplinary class on soft matter will be offered to students at both institutions.