Mixing, Migration, and Structure of Suspensions in Pressure-Driven Flows

压力驱动流中悬浮液的混合、迁移和结构

• 批准号: 1033631
• 负责人: James Gilchrist
• 金额: $ 29万
• 依托单位: Lehigh University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-08-15 至 2013-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1033631&HistoricalAwards=false
• 关键词: Mixing; Migration; Structure; Suspensions; Pressure

Suspensions of a moderate particle volume fraction tend to demix in nonlinear shear. Although this effect has been studied extensively in simple flows to determine how suspension rheology results in migration, few studies have considered how migration occurs in more complicated flows. Migration in industrial processes has long complicated process development and has become increasingly important as researchers strive to process and analyze blood and other biological suspensions in complicated BioMEMS flows. The objectives of this research are to broaden our fundamental understanding of flowing suspensions by considering how the fundamental symmetries within flows interplay with the underlying suspension structure. In 1D, 2D and 3D microchannel flows commonly used in BioMEMS, the competition between suspension demixing via shear migration resulting from multibody hydrodynamic interactions and chaotic advection generated within microchannels designed to enhance mixing will be investigated. Direct measurement of flow and concentration profiles will be performed using high speed 3D confocal laser scanning microscopy (CLSM). This technique, coupled with a flow-stop-scan protocol, allows direct measurement of suspension structural anisotropy that generates the normal stresses that result in migration. These studies will be extended to examination of technologically relevant fluids, including polydisperse suspensions, electrostatic-stabilized suspensions, suspensions in viscoelastic media, and whole blood. Because flow, migration, and local structure is determined directly using CLSM, the effect of the addition of monosized suspension on cell migration and rouleau formation can be examined. In addition, continuum models will be used to explore the coupling between suspension migration and the underlying topology in chaotic flows. The intellectual merits and transformative aspects of this study include the development of directly measuring suspension structure and demonstrating the coupling between chaos and segregation in flowing suspensions. The broader impacts of this research include a new paradigm of using chaotic advection as a template for self-organization in suspensions that could revolutionize suspension processing from the microscale to industrial-scale, a potential new platform for whole blood fractionation and detection, and integration of graduate, undergraduate, middle school hands-on and web-based learning of the broader field of particle technology. Specifically, an Image of the Week website that presents the results of this research and university-wide microscale and nanoscale research to a broader community will be developed. Likewise, in order to introduce the broader subject of particle technology to early scientists, collaboration with a local middle school to develop a hands-on learning module for exploring granular media will engage students from low social economic status and otherwise underrepresented minority groups within engineering and the sciences.

中等颗粒体积分数的悬浮液倾向于在非线性剪切中分层。 尽管这种效应已在简单流动中进行了广泛研究，以确定悬浮液流变学如何导致迁移，但很少有研究考虑迁移在更复杂的流动中如何发生。 工业过程中的迁移长期以来一直是复杂的过程开发，并且随着研究人员努力处理和分析复杂 BioMEMS 流中的血液和其他生物悬浮液而变得越来越重要。 这项研究的目的是通过考虑流动中的基本对称性如何与底层悬浮结构相互作用来扩大我们对流动悬浮的基本理解。 在 BioMEMS 中常用的 1D、2D 和 3D 微通道流中，将研究通过多体流体动力学相互作用产生的剪切迁移进行的悬浮液分层与旨在增强混合的微通道内产生的混沌平流之间的竞争。 将使用高速 3D 共焦激光扫描显微镜 (CLSM) 直接测量流量和浓度分布。 该技术与流动停止扫描协议相结合，可以直接测量悬浮液结构各向异性，从而产生导致迁移的法向应力。这些研究将扩展到技术相关流体的检查，包括多分散悬浮液、静电稳定悬浮液、粘弹性介质悬浮液和全血。 由于流动、迁移和局部结构是使用 CLSM 直接确定的，因此可以检查添加单一尺寸悬浮液对细胞迁移和花圈形成的影响。 此外，连续介质模型将用于探索混沌流中悬浮液迁移与底层拓扑之间的耦合。 这项研究的智力优点和变革性方面包括直接测量悬浮结构的发展以及证明流动悬浮液中混沌与分离之间的耦合。 这项研究的更广泛影响包括使用混沌平流作为悬浮液自组织模板的新范式，这可能彻底改变悬浮液处理从微型规模到工业规模的情况，一个潜在的全血分离和检测新平台，以及集成研究生、本科生、中学更广泛的粒子技术领域的实践和基于网络的学习。 具体来说，将开发一个“本周图像”网站，向更广泛的社区展示这项研究以及大学范围内的微米级和纳米级研究的结果。 同样，为了向早期科学家介绍更广泛的粒子技术学科，与当地一所中学合作开发一个探索颗粒介质的实践学习模块，将吸引来自社会经济地位较低的学生以及工程学和其他领域代表性不足的少数群体。科学。