微通道受限空间内颗粒诱导微观涡结构对其自组织影响机理研究

Transport of micro-scale particle-liquid flow is an important fundamental problem and is gaining increasing attentions in recent decades. However, transport details and mechanisms of particle transport phenomenon are still not fully understood, which even raises significant debates (such as Physics of Fuids, 27: 043302, 2015; Journal of Fluid Mechanics, 786: R3, 2016). In this project by combining theoretical analysis and experimental measurement, we will conduct thorough and systematic investigation on the coupling two phase transport mechanisms of interactions between liquid-particle, particle-particle, particle-wall, and reveal the underlying physical nature and orderliness of the transport process. The main work includes: 1) revealing important coupling mechanisms and micro-scale transport details of interaction between liquid and particles, quantitatively measuring and reconstructing the 3D flow field near the particles, and fully understanding the rising and development of this micro flow; 2) further exploring the physical nature of particle-particle, particle-wall interaction, developing and establishing multi-scale theoretical model to describe the mechanics and kinetics behavior of multi-particles by analyzing its micro-scale acting force and dynamic behaviors, revealing the underlying physical mechanics, nature and rules of particle dynamics; 3) fully understanding the behavior and mechanism of the 3D structure of particle self-assembled patterns and the orderliness of this phenomenon, so as to resolve the debates in literature. Based on the above investigation, the theoretical system for liquid-particle two phase flow in micro scale will be established, which can further provide guidance to the development of industrial applications.

针对当前对受限空间内颗粒自组织现象的存疑和争议、以及由此产生的微颗粒分选/操控技术中效率进一步提高的桎梏，本课题拟从理论分析和实验观测两方面出发，围绕该现象的本质机理和微观流动细节，开展深入系统研究，包括：1）从颗粒诱导微观涡结构出发，全面掌握该流动的产生机制、发展演变及其对颗粒动力学行为的影响，揭示液体-颗粒的深层次耦合作用机制；2）探明液体-颗粒、壁面-颗粒、颗粒-颗粒复合作用下，颗粒、颗粒偶的运动特征与相应的微观流场结构，全面掌握颗粒间相互作用机制与相对运动规律；3）把握颗粒群全流程范围的自组织三维排布与迁移规律，从根源上消除当前对颗粒沿微通道轴向分布的争议，并以此揭示颗粒浓度对其自组织的影响规律，进而探讨颗粒分选/操控系统效率提升的要素，回归应用需求。上述研究旨在构建系统完整的、适用于高通量颗粒输运的自组织理论，推动和指导相关技术进步，具有重要科学意义。

微通道受限空间内颗粒的自组织现象是一个复杂的、多因素耦合的高度非线性传递过程，同时也是诸多微流控技术实现功能的共性技术难点。本项目针对当前对受限空间内颗粒自组织现象的存疑和争议，从理论分析和实验观测两方面出发，围绕该现象的本质机理和微观流动细节，开展了一系列深入系统研究。主要研究内进展包括：1）从颗粒诱导微观涡结构出发，全面掌握该流动的产生机制、发展演变及其对颗粒动力学行为的影响，揭示液体-颗粒的深层次耦合作用机制；2）探明液体-颗粒、壁面-颗粒、颗粒-颗粒复合作用下，颗粒、颗粒偶的运动特征与相应的微观流场结构，全面掌握颗粒间相互作用机制与相对运动规律；3）把握颗粒群全流程范围的自组织三维排布与迁移规律，从根源上消除当前对颗粒沿微通道轴向分布的争议，并以此揭示颗粒浓度与流动参数对其自组织的影响规律；4）进一步针对研究中发现的有趣现象，探索了平动受限颗粒（仅具备一维转动自由度）的动力学行为及其与微通道内流体的耦合作用机制，命名了其在流场中的典型运动模态，进而重点分析了其诱导的微观涡结构对微通道内传热与传质效率的促进效应。基于上述研究，构建了较为系统完整的微通道内颗粒自组织输运理论，从本源物理机理上调和了此前学术界对颗粒自组织输运过程中轴向间距的争议，有望推动和指导相关技术进步，具有科学意义。