Collaborative Research: A Dynamical Systems Approach to Shepherding and Sorting Microparticles in Fluids

从生物医学研究到精密制造，需要在微观尺度上控制悬浮在流体中的固体颗粒的运输和定位的工程问题经常出现。在颗粒易碎（如生物细胞）或高通量至关重要的情况下，需要在颗粒和操纵器之间没有直接机械接触的情况下实现颗粒操作的技术。该奖项支持基础研究，该研究推进了一种策略，即使用细长的振动探针来激发颗粒负载流体中的流动模式，从而以所需的方式平流颗粒。初步结果表明，该方法不仅可以实现粒子的传输和定位，而且可以根据粒子的大小和几何形状等物理属性对粒子进行分离。该项目需要研究小组成员在数学、计算和实验领域的协调活动。这项活动的成果将包括具有多种实际意义的科学成果和跨传统学科培养本科生和研究生的新机制。要解决的技术问题包括发展具有不同程度细节的数学模型，代表振动探头系统附近的流体流动，发展由这种流动平流的惯性粒子的时间平均动力学的近似解析模型，以及发展用于粒子传输和分选的典型问题的顶层控制策略。所有这些都将建立在项目团队成功的初步研究基础上，并将通过利用高保真计算模型的数值模拟和利用正在开发的独特实验室平台的物理实验进行验证。

Engineering problems requiring the controlled transport and positioning of solid particles suspended in fluids on a microscopic scale arise in contexts ranging from biomedical research to precision manufacturing. Technology enabling particle manipulation without direct mechanical contact between particles and manipulators is required in situations when the particles are fragile (like biological cells) or when high throughput is critical. This award supports fundamental research advancing a strategy whereby slender vibrating probes are used to excite patterns of flow in particle-laden fluids that in turn advect particles in desired ways. Preliminary results indicate that this approach can be used not only to achieve particle transport and positioning but also to separate particles according to physical attributes like size and geometry. The project requires coordinated activity by members of the research team in mathematical, computational, and experimental domains. Outcomes from this activity will include both scientific results with diverse practical implications and novel mechanisms for training undergraduate and graduate students across traditional disciplinary lines.Technical issues to be addressed include the development of mathematical models with varying degrees of detail representing fluid flows near systems of vibrating probes, the development of approximate analytical models for the time-averaged dynamics of inertial particles advected by such flows, and the development of top-level control strategies for archetypical problems in particle transport and sorting. All of these will build upon successful preliminary studies by the project team and will be validated with numerical simulations exploiting high-fidelity computational models and with physical experiments exploiting a unique laboratory platform under development.