携带颗粒的流动广泛存在于自然界及能源、环保、化工、医药等各类工业生产及应用过程中。对于微米级细颗粒，颗粒间的粘附作用较强，使得颗粒极易互相粘附，形成大的颗粒团或沉积在壁面，例如燃煤电厂设备的结渣、航天系统关键器件设备上的尘埃沉积、微流控系统的堵塞、药物粉体输送过程中的团聚等，将导致系统效率降低，严重情况下造成系统失稳引发安全问题。从颗粒动力学的角度揭示颗粒团聚机理和槽道堵塞机制，深入理解颗粒间复杂相互作用与宏观系统的团聚堵塞行为之间的关联，能够为颗粒物应用与防控中促进或抑制颗粒沉积和团聚、避免堵塞现象的发生提供指导，具有重要的科学意义和应用价值。针对上述背景，本文基于离散动力学方法框架，围绕颗粒间流体长程作用下细颗粒的团聚与堵塞过程开展研究，发展了基于液桥理论的湿颗粒离散动力学方法，并关注于颗粒间流体长程作用下不同尺度系统中的不同关键颗粒运动行为，分别从迁移、碰撞、团聚、堵塞等角度开展系统性研究。首先，将液桥理论引入颗粒碰撞动力学方程中，并建立湿颗粒接触判断准则，发展了湿颗粒离散动力学方法。针对微米颗粒堵塞槽道的现象，开展了从颗粒碰撞、沉积到颗粒团聚、堵塞过程的动态模拟。揭示了液桥作用对堵塞过程的影响规律，获得了堵塞过程的关键控制参数，构建了堵塞相图以描述槽道堵塞-非堵塞的转变，分析了液桥作用与颗粒-流体相互作用的竞争关系，并与干颗粒间范德华作用的效果进行了对比。其次，在系统尺度更大、流动更复杂的湍流中探究了颗粒碰撞与团聚过程。揭示了颗粒惯性和液桥作用对湍流中颗粒迁移、碰撞、粘附、反弹过程的影响机理。利用以法向碰撞速度定义的韦伯数对颗粒碰撞后的粘附概率进行模化并提出了预测公式。进而，获得了液桥作用下颗粒在湍流中的碰撞及团聚过程的演化规律，分析了液桥作用强度与颗粒团聚程度、颗粒团聚体结构之间的关联。最后，结合Oseen动力学，在颗粒碰撞团聚理论中引入了颗粒-流体-颗粒相互作用，分析了颗粒-流体-颗粒相互作用带来的“多体效应”对颗粒碰撞频率及速度、颗粒局部富集、团聚体大小及结构的影响规律，并揭示了颗粒-流体-颗粒相互作用与液桥相互作用的协同作用效果。

Particulate flow is ubiquitous in natural phenomena and industrial applications covering energy and power engineering, environmental protection, chemical industry, pharmaceutical process, and other fields. The attraction generated by the interaction between microparticles makes it easy to form large agglomerates and deposit on walls, including slagging of coal-fired power plant equipment, clogging of microfluidic systems, agglomeration during pharmaceutical powder delivery, which result in reduced system efficiency and in serious cases systems instability may lead to potential safety problems. Revealing the mechanism of particle agglomeration and clogging from the perspective of particle dynamics, and deeply understanding the correlation between the complex particle-particle interactions and the agglomeration and clogging behavior of macroscopic systems, can provide guidance for promoting or inhibiting particle deposition and agglomeration, and avoiding the occurrence of clogging, which are of great significance for theoretical research and industrial application. In this thesis, the agglomeration and clogging process of small particles under long-range interactions is studied by developing a muti-timestep discrete element method for wet particles based on Hertz theory and liquid bridge theory. The behaviors of particles in systems with different scales are systematically studied from the perspectives of migration, collision, agglomeration, and clogging.A discrete element method for the dynamics of wet particles is developed by embedding a cohesive contact model in presence of pendular liquid bridges. The dynamic simulation of the process from particle collision and deposition to particle agglomeration and breakage is established for the phenomenon of clogging of channels by microparticles. The influence of liquid bridge interaction on the clogging process is revealed, and the key parameters for controlling the clogging process are obtained. A clogging phase diagram is constructed to quantify the clogging-nonclogging transition. The competition between particle-particle liquid bridge interaction and particle-fluid interaction is quantitatively discussed in terms of particle velocity and slip velocity. The results of wet particles are compared with that of dry particles with the van der Waals interaction.Then, the process of particle collision and agglomeration is explored in the more complex turbulence in a larger-scale system. The influence principle of particle inertia and liquid bridge interaction on the process of particle migration/collision/sticking /rebound in turbulence is revealed, and the sticking probability after collision is modeled by Weber number defined by normal collision velocity, and a prediction formula is proposed. Furthermore, the evolution law of the collision and agglomeration process of particles in turbulence in presence of liquid bridge is obtained, and the correlation between the strength of liquid bridge interaction and the degree of particle agglomeration and the structure of particle agglomerates is analyzed.Finally, combined with Oseen dynamics, the particle-particle hydrodynamic interaction is introduced into the theory of particle collision and agglomeration, and the influence mechanism of the multi-body effect caused by the particle-particle hydrodynamic interaction on the particle collision frequency and velocity, local particle concentration, size and structure of particle agglomerates is revealed, and the synergistic effect of particle-particle hydrodynamic interaction and liquid bridge interaction is further elaborated.