RUI: Lagrangian Chaos: Phase Separation, Coalescence and Aggregation

这个凝聚态物理项目集中在拉格朗日混沌（混沌粒子运动和流体混合）对多相过程的影响：相分离和聚结;液滴破碎和悬浮粒子聚集。 从根本和实际的角度来看，人们对这些进程都很感兴趣。 以前的研究已经研究了简单剪切流对多相过程的影响，但是，这些研究没有考虑不同剪切区域之间的液滴平流。 平流是特别重要的，鉴于最近的发现，拉格朗日混沌发生的流动本身并不混乱或湍流;相反，混乱的轨迹发生，甚至在良好的秩序，层流。 这项研究将概括以前用于表征多相过程的措施（例如，毛细管数）来解释一般的平流，特别是拉格朗日混沌。 在由交替涡链组成的简单二维和三维流体流动中，提出了一系列的实验和数值模拟。这些研究完全是与本科生一起完成的;这项研究为他们提供了一个机会，让他们在必须做出重要职业决定的时候体验新颖的研究。此外，他们学到的技术帮助他们为研究生院和/或学术，工业或政府职业做好准备。拉格朗日混沌是流体流动中的杂质可以遵循混沌轨迹的过程，即使流动本身非常简单且有序。 提出了实验来研究拉格朗日混沌对多相过程的影响，该过程涉及包含第二不混溶流体（如水中的油）或悬浮颗粒的流体。 研究将在二维和三维流动中进行，并将通过数值模拟来补充实验。该研究适用于广泛的工业过程，因为许多应用采用多相流体系统。 以前的研究主要集中在简单的剪切流如何将不混溶的流体破碎成较小的液滴或防止它们合并成较大的液滴。然而，这些研究没有考虑液滴在不同剪切区域之间的混沌运动。拟议中的研究将填补这一认识上的差距。这些研究完全是与本科生一起完成的;研究为他们提供了在他们必须做出重要职业决定的时候体验新研究的机会。F此外，他们学习的技术有助于他们为研究生院和/或学术界，工业或政府职业做好准备。

This condensed matter physics project concentrates on the effects of Lagrangian chaos (chaotic particle motion and fluid mixing) on multiphase processes: phase separation and coalescence; droplet break-up, and aggregation of suspended particles. There is significant interest in these processes, both from fundamental and practical perspectives. Previous research has studied the effects of simple shearing flows on multiphase processes; however, those studies did not consider advection of drops between regions with varying shear. Advection is particularly important in light of recent discoveries that Lagrangian chaos occurs for flows that are not chaotic or turbulent themselves; rather, chaotic trajectories occur even in well-ordered, laminar flows. This research will generalize previous measures used to characterize multiphase processes (e.g., the Capillary number) to account for advection in general and Lagrangian chaos in particular. A series of experiments and numerical simulations are proposed in simple two- and three-dimensional fluid flows composed of chains of alternating vortices. The studies are done entirely with undergraduates; the research provides them with an opportunity to experience novel research at a time when they must make important career decisions. Furthermore, the techniques that they learn help prepare them for graduate school and/or careers in academics, industry or government.%%%Lagrangian chaos is the process by which impurities in a fluid flow can follow trajectories that are chaotic, even if the flow itself is very simple and well-ordered. Experiments are proposed to study the effects of Lagrangian chaos on multiphase processes, which involve fluids containing either a second, immiscible fluid (such as oil in water) or suspended particles. Studies will be done in both two- and three-dimensional flows, and the experiments will be complemented by numerical simulations. The research is applicable to a wide range of industrial processes, since many applications employ multiphase fluid systems. Previous research focused on how simple shearing flows break up immiscible fluids into smaller droplets or prevent them from coalescing into larger drops. However, those studies did not consider chaotic motion of drops between regions of varying shear. The proposed research will fill the gap in this understanding. The studies are done entirely with undergraduates; the research provides them with opportunities to experience novel research at a time when they must make important career decisions. F Furthermore, the techniques that they learn help prepare them for graduate school and/or careers in academics, industry or government.***