COLLABORATIVE RESEARCH: The statistical mechanics of bed load sediment transport: Scaling particle motion to fluvial form

美国的溪流和河流处于不断变化的状态，这是由于建造了数万座水坝，现在正在退役，以及水资源利用和土地利用的变化影响了河流的流量。广泛的实地研究记录了影响鱼类和其他生物群的砾石河流的几何形状和基底的复杂变化。由于不规则的，间歇性的性质所携带的湍流河流的砂和砾石的运动，目前的泥沙输运模型无法预测这些关键的河岸变化。该项目利用基于物理学的超级计算机算法和先进的实验室成像技术，调查和描述单个颗粒和湍流涡旋水平上的沉积物运动。将统计物理原理应用于这些超级计算机和实验室结果，以产生一个理论框架，预计该框架将提供预测能力，从而为该国水道发生的巨大变化提供政策指导。实验工作涉及砾石床水槽和高速视频，以说明河床地形变化的基础，以及这个问题中的特征长度尺度是如何由质点运动的分布决定的。实验室实验将由粒子和量子分辨的超级计算机模拟与动量耦合来复制。这项工作的目的也是参数化统计理论的情况下，交替酒吧形成，从而提供了基础，进一步澄清渠道规模的形态动力学问题，其中存在的斑块，稀薄的运输conditions.This奖是共同资助的地貌和土地利用动力学计划和国家战略计算倡议。

The streams and rivers of the United States are in a state of flux due to the building, and now decommissioning, of tens of thousands of dams, as well as changes in water use and land use influencing river flows. Extensive field studies have documented complex changes to the geometry and substrate of gravel-bedded rivers affecting fish and other biota. Due to the patchy, intermittent nature of the motion of sand and gravel carried by turbulent river flow, current models of sediment transport are unable to predict most of these critical riparian changes. This project investigates and describes sediment motion at the level of individual grains and turbulent eddies using physics-based supercomputer algorithms and advanced laboratory imaging techniques. Statistical physical principles are applied to these supercomputer and laboratory results to produce a theoretical framework that is expected to provide predictive capabilities, and thus, policy guidance regarding dramatic changes occurring in the country's waterways.The experimental work involves gravel-bed flumes and high-speed video to illustrate the basis for changes in streambed topography, and how the characteristic length-scales in this problem are determined by the distribution of particle motions. Laboratory experiments will be replicated by particle- and turbulence-resolving supercomputer simulations coupled in momentum. The work also is aimed at parameterizing statistical theory for the case of alternate bar formation, thus providing the basis for further clarifying channel-scale morphodynamics problems in which patchy, rarefied transport conditions exist.This award is cofunded by the Geomorphology and Land-use Dynamics Program and the National Strategic Computing Initiative.