The Role of Complex Fluids on the Flow and Instabilities of Particle-Laden Liquids

在先进技术中，小型设备（例如微流体设备）在细胞检测中发挥着至关重要的作用。这些设备依赖于在流动条件下仔细排列颗粒，这一过程通常需要控制颗粒在流动中的运动。通常，这种运动是通过使用电、磁、声学或光学等外部场来实现的，但这种方法有局限性并且取决于特定的粒子特性。另一种方法称为弹性惯性聚焦，它平衡流内的自然力，以沿着设备的中心线集中颗粒。虽然这种方法有望以一种非侵入性的方式实现所需的粒子运动，但它也面临着挑战。在处理某些类型的流体（聚合物或非牛顿流体）时，由于弹性不稳定性的出现，颗粒的处理速度受到限制。为了应对这些挑战，该研究将开发超越微流体装置限制的新颖实验方法和数值模拟。实验和模拟结合起来应该可以更全面地了解流体和颗粒相中速度和颗粒模式的分布。除了推进科学知识之外，这项研究还对教育产生更广泛的影响。该团队致力于为跨学科 STEM 教育和培训提供独特的机会。目标是让多元化的学生和研究人员成为下一代跨学科科学家和工程师。计划中的外展活动包括为 K-12 项目创建实践活动，重点关注代表性不足的学生。该项目旨在揭示对复杂溶剂中携带非布朗粒子的流体流动所涉及的物理学的新的基本理解。拟议的工作将高分辨率数值模拟与实验相结合，其中包括时间分辨和高分辨率平面粒子图像测速（PIV）、粒子跟踪测速（PTV）和磁共振成像（MRI），特别关注复杂流体中球形粒子的悬浮液。该项目采用综合数值和实验研究的综合方法，探索了考虑颗粒浓度和流体流变特性所定义的特定条件。主要目标是更好地物理理解颗粒和复杂流体存在下的流动特性和不稳定性。更好地了解这些流动对各个行业都有影响，包括喷墨印刷、生物医学设备，甚至提高石油采收率。这项研究有可能为在实际应用中有效管理颗粒流动提供宝贵的见解和工具，从而造福社会。该奖项反映了 NSF 的法定使命，并通过使用基金会的智力价值和更广泛的影响审查标准进行评估，被认为值得支持。

In advanced technologies, small devices, such as microfluidic devices play a crucial role in cell detection. These devices rely on carefully arranging particles under flowing conditions, a process often requiring the controlled movement of particles across the flow. Typically, this movement is achieved by using external fields like electricity, magnetism, acoustics, or optics, but this method has limitations and depends on specific particle properties. An alternative approach known as elasto-inertial focusing, instead balances natural forces within the flow to concentrate particles along the centerline of the device. While this approach promises a noninvasive way to achieve the desired particle movement, it has challenges. When dealing with certain types of fluids (polymeric or non-Newtonian), there is a limit to how fast particles can be processed due to the onset of elastic instabilities. To address these challenges, the research will develop novel experimental methods and numerical simulations that go beyond the limitations of microfluidic devices. Experiments and simulations together should provide a more thorough understanding of the distribution of velocity and particle patterns in both the fluid and particle phases. In addition to advancing scientific knowledge, this research has a broader impact on education. The team is committed to providing unique opportunities for interdisciplinary STEM education and training. The goal is to equip a diverse group of students and researchers to emerge as the next generation of interdisciplinary scientists and engineers. The planned outreach activities include creating hands-on activities for K-12 programs, with a focus on underrepresented students.This project aims to uncover new and essential understandings of the physics involved in fluid flows carrying non-Brownian particles within complex solvents. The proposed effort combines highly resolved numerical simulations with the experiments, which include time-resolved and highly resolved planar particle image velocimetry (PIV), particle tracking velocimetry (PTV), and Magnetic resonance imaging (MRI), focused specifically on suspensions of spherical particles in complex fluids. Using a comprehensive approach that integrates both numerical and experimental studies, the project explores specific conditions defined by considerations of particle concentrations and fluid rheological properties. The primary goal is to provide a better physical understanding of both the flow characteristics and instabilities in the presence of particles and complex fluids. A better understanding of these flows has implications for various industries, including inkjet printing, biomedical devices, and even enhanced oil recovery. This study has the potential to benefit society by providing valuable insights and tools for effectively managing particle-laden flows in practical applications.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.