推移质输移的随机多尺度特性机理

Bed load transport is a typical stochastic and multi-scale process, which can be performed at the processes of individual particle motion, bed forms and bed load transport rates. Previous studies generally focused on the stochastic characteristics of just processes. On the one hand, the studies mostly focus on the analysis of stochastic and multi-scale characteristics themselves, without model development. On the other hand, even the very rare models only producing the stochastic and statistic characteristics, without revealing the physical mechanics, let alone the coupled dynamics of bed load flux, bed topography and flow turbulence. Employing the methods of flume experiments and theoretical analysis, this project will observe near bed flow, bed topography dynamics and bed load flux simultaneously, aiming to understand and quantify the interaction of flow turbulence, bed topography and sediment transport and their dependence on particle-size distribution and derive stochastic transport models that relate microscale dynamics of particle movement to the macroscale statistics of sediment transport via minimum complexity stochastic models. Particularly, it will reveal the coupled dynamics of bed load transport, turbulence flow and bed topography dynamics through experimental data to verify the minimum complexity stochastic models and their calculation methods. This project will help to understand in depth for the basic theories of bed load transport, and provide theoretical support for transport flux, bed topography and flow resistance.

推移质输移具有典型的随机和多尺度特性，这种特性在单颗粒运动、床面形态演化及输沙率等过程方面都有体现。以往的研究多孤立地针对某个过程，一方面多分析随机多尺度特性本身，缺乏建模；另一方面少有的模型对物理过程机理的揭示不够深入，更缺乏对不同过程之间相互反馈的研究。本项目拟采用水槽实验和理论分析相结合的手段，对近床面水流、床面形态的动态演化及输沙率进行同步观测，揭示水流—颗粒、颗粒—颗粒及颗粒—边界之间复杂的相互作用；结合包括统计力学的随机过程理论，研究各个过程的随机多尺度特征，建立能描述从跨一定尺度的、尽可能简化的随机模型，模拟床面动态特征与输沙率的随机性及统计特征；通过实验资料对建立的简化模型和计算方法进行验证，特别是进一步揭示这种随机和多尺度特性背后的物理过程，及各个过程的相互反馈作用。研究成果有助于深入认识推移质运动的基础理论，为输沙率、床面形态及河流阻力等的研究提供理论基础参考。