河口细颗粒泥沙的湍流絮凝动力学机制

河口悬浮细颗粒泥沙，极易絮凝形成粒径跨越几个数量级、形态各异的絮团或聚集体，它们可视为内含丰富水份与孔隙，由无机质和有机质等多种介质组成的微型生态系统。絮凝不仅仅是细颗粒泥沙研究无法回避的基本过程，而且其在元素与营养盐循环、污染物迁移扩散等过程中也至关重要，因此多年来一直成为泥沙运动基本理论的关键和颗粒聚集体多学科交叉研究的热点。尽管如此，目前关于湍流驱动的细颗粒泥沙絮凝动力学机制并不十分清楚。本项目通过设计研制絮团发育的实验控制系统，开展河口典型动力结构下絮凝与湍流的现场原位观测，建立基于群体平衡方程的絮凝动力学模型，围绕絮团的粒径分布及多峰结构变化，阐述絮团粒径分布的湍流动力指示意义，探讨影响絮团聚并、破碎的平衡过程与生消机制，揭示絮团与湍流的相互作用机制。项目成果可以丰富细颗粒泥沙研究的基本理论，为深化絮团微型生态系统的多学科交叉研究提供物理机理支撑。

Flocculation of fine-grained cohesive sediments in estuaries, a microecosystem composed of multi-source particles whose size distributions spanning widely and property diversity, has been the key in sediment movement theory and a hot topic in the interdisciplinary research over the years. Not only an unavoidable basic process in fine-grained sediments research it is, but also an important role in native element and nutrient circulation, pollutant migration and diffusion. The turbulence-induced flocculation dynamics mechanism is not clear up to now, although remarkable progresses have been made in exploration of its properties, influencing factors and simulation of population balance equation (PBE) over the last decades. This project is aimed to reveal interaction mechanism of flocculation and turbulence, which includes establishing the its kinetic model based on PBE, describing the significance of turbulence to multi-modality transformation and particle size distributions, and further discussing flocculation aggregation and break-up mechanism driven by internal source-sink and external dynamic process, with comprehensive and detailed self-design systems: one for in-lab controlling flocculation and another for in-situ field observation under typical estuarine dynamic structures. The results can enrich the fundamental theory of fine-grained cohesive sediments as well as provide the physical mechanism supports and methods to deepen the systematic multi-disciplinary study into flocculation microecosystem.