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脱粒。 尽管已在简单的流中进行了广泛的研究，以确定悬浮流变性如何导致迁移的结果，但很少有研究考虑了在更复杂的流中如何发生迁移。 工业过程中的迁移长期以来已经复杂化了过程的发展，并且随着研究人员努力处理和分析复杂生物元流中的血液和其他生物学悬浮液，变得越来越重要。 这项研究的目标是通过考虑如何与基本悬架结构相互作用，扩大我们对流动悬浮液的基本理解。 在生物元中常用的1D，2D和3D微通道流中，将研究用于增强混合的微型通道中产生的多体流体相互作用和混乱的对流而导致的剪切迁移的悬架分解之间的竞争。 将使用高速3D共聚焦激光扫描显微镜（CLSM）进行流动和浓度轮廓的直接测量。 该技术与流动扫描协议相结合，可以直接测量悬浮结构各向异性，从而产生导致迁移的正常应力。这些研究将扩展到技术相关的流体，包括多分散悬浮液，静电稳定的悬浮液，粘弹性介质中的悬浮液和全血。 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体悬浮液对细胞迁移和Rouleau形成的影响。 此外，连续模型将用于探索悬架迁移与混沌流中潜在拓扑之间的耦合。 这项研究的智力优点和变革性方面包括开发直接测量悬架结构，并证明流动悬浮液中混乱与隔离之间的耦合。 这项研究的更广泛的影响包括新的范式，该范式是使用混乱的对流作为悬架中自组织的模板，这些模板可能会彻底改变从微观到工业规模的悬架处理，这是一个潜在的全血分馏和检测平台，用于研究生，本科生，中学，基于中学，基于中学，基于中学，基于中学，基于中学，基于网络的学习。 具体而言，将开发向更广泛社区的本周网站的图像，并向更广泛的社区提供了这项研究的结果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主题，与当地的中学合作开发了一个动手学习模块以探索颗粒状媒体，这将吸引来自低社会经济地位的学生，否则工程和科学中代表性不足的少数群体群体不足。