Dynamics of capillary threads and high-viscosity droplets in microfluidic systems

微流体系统中毛细管线和高粘度液滴的动力学

• 批准号: 0932925
• 负责人: Thomas Cubaud
• 金额: $ 24.05万
• 依托单位: SUNY at Stony Brook
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-09-01 至 2012-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0932925&HistoricalAwards=false
• 关键词: Dynamics; capillary; threads; viscosity; droplets

0932925CubaudThis award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5). This study describes an integrated suite of activities for the precise manipulation of high-viscosity fluids in a sheath of immiscible less viscous fluids at the small-scale. Microfluidics is a fast developing field, yet investigations of multi-fluids flows with large viscosity contrasts have remained limited. Numerous industrial and biological fluids such as heavy oils and solvents, however, exhibit widely varying viscosities. Their manipulation at the small-scale would provide new capabilities for lab-on-chip devices. Transparent high-pressure microdevices will display the mechanisms associated with the lubrication of high-viscosity materials in small fluidic passages. Two investigations are planned. The first pursues the dynamics of viscous core-annular flows in diverging-converging microfluidic chambers. Buckling instabilities of slender viscous structures in diverging microchannels will be exploited to control the threads morphology and induce breakup. The stability of thin intercalating films between threads and microchannel walls will be investigated for formation of ripples and forced wetting phenomena. The second investigation studies high-viscosity droplets in chambers and physicochemical stratifications. The hydrodynamic coupling and coalescence between high-viscosity droplets will be examined in extensional geometries. The PI will investigate the possibility to enhance micromixing by inducing coalescence between low- and high-viscosity droplets. Finally, physicochemical stratifications injected in cross-flow will engineer viscous droplets. This system will provide a simple model of multi-step flow reactors. This research program will characterize novel fluid behaviors in a relatively unexplored region of microscale multi-fluid flows. In particular, the alteration of convective time-scales using extensional microgeometries permits the manipulation of complex phenomena such as buckling, wetting, coalescence, breakup, and relaxation of highly-viscosity microstructures. Simple flow geometries will elucidate the interrelation between these phenomena. This study will integrate a systematic experimental approach with numerical simulations and theoretical predictions to aid development of next-generation microfluidic devices. This work combines research and training of a large spectrum of students, including underrepresented, high school, undergraduate, and graduate students. A central objective of the educational activities is to attract and nurture students in the science and engineering fields. An important aspect of this project is to devise methods to control novel continuous emulsification processes between highly viscous oils and solvents, such as ethanol. Thus, the technical expertise that will be developed can potentially provide disruptive advances for making more efficient engines, enhancing oil recovery, and developing continuous multi-step flow reactors for bio-fuel production.

0932925CubaudThis奖是根据2009年美国复苏和再投资法案（公法111 - 5）资助。这项研究描述了一套完整的活动，精确操纵高粘度流体在鞘中的不混溶的粘性较小的流体在小规模。微流体技术是一个快速发展的领域，但对具有大粘度差的多流体流动的研究仍然有限。然而，许多工业和生物流体，如重油和溶剂，表现出广泛变化的粘度。它们在小规模上的操纵将为芯片实验室设备提供新的能力。透明的高压微器件将显示与小流体通道中的高粘度材料的润滑相关的机制。计划进行两项调查。第一个追求的动力学的粘性核心，环形流在发散收敛微流体室。发散微通道中细长粘性结构的屈曲不稳定性将被用来控制螺纹形态和诱导破裂。线和微通道壁之间的薄插层膜的稳定性将被调查的波纹和强迫润湿现象的形成。第二项调查研究了高粘度液滴在室和物理化学分层。高粘度液滴之间的流体动力学耦合和聚结将在拉伸的几何形状检查。PI将研究通过诱导低粘度和高粘度液滴之间的聚结来增强微观混合的可能性。最后，物理化学分层注入横流将工程粘性液滴。该系统将提供多步流动反应器的简单模型。这项研究计划将在微尺度多流体流动的相对未开发的区域表征新的流体行为。特别是，对流时间尺度的改变，使用延伸的微观几何形状允许操纵复杂的现象，如屈曲，润湿，聚结，分裂，和松弛的高粘度的微观结构。简单的流动几何学将阐明这些现象之间的相互关系。这项研究将整合系统的实验方法与数值模拟和理论预测，以帮助开发下一代微流体设备。这项工作结合了大量学生的研究和培训，包括代表性不足，高中，本科和研究生。教育活动的一个中心目标是吸引和培养科学和工程领域的学生。该项目的一个重要方面是设计控制高粘度油和溶剂（如乙醇）之间的新型连续乳化过程的方法。因此，将开发的技术专长可能为制造更高效的发动机、提高石油采收率和开发用于生物燃料生产的连续多步流动反应器提供颠覆性的进步。