Collaborative Research: Grain to Channel Scale Experimental and Numerical Investigation of Cohesive Sediment Transport

合作研究：粘性沉积物迁移的颗粒到通道尺度的实验和数值研究

• 批准号: 2150796
• 负责人: Judy Yang
• 金额: $ 34.32万
• 依托单位: University of Minnesota-Twin Cities
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2022
• 资助国家: 美国
• 起止时间: 2022-04-15 至 2025-03-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2150796&HistoricalAwards=false
• 关键词: Collaborative; Research; Grain; Channel; Scale

Each year, the United States loses billions of dollars in property and large areas of habitat to erosion. To mitigate erosion-related damages and habitat losses, restoration projects import sediment to eroded areas. The success of these restoration efforts depends on their ability to retain sediment, so that restoration design requires a good understanding of sediment transport. Currently, there are established methods for predicting the transport of non-cohesive sediment, such as sand and gravel, relative to flow conditions and sediment particle size. However, it remains difficult to predict the transport of cohesive sediment, such as clay or mud, which is ubiquitous in aquatic ecosystems and consists of very fine particles. Predicting cohesive sediment transport is challenging because these fine particles have a strong tendency to stick together and form aggregates. These aggregates greatly change the effective size of the sediment particles and their interaction with the flow. This project will combine experiments and numerical simulations at a range of scales to understand how fine cohesive particles form aggregates and how aggregation controls the transport of sediment in water. Predictive equations for cohesive sediment transport will be developed. The results of this study will help improve designs of restoration projects to mitigate erosion-driven property and habitat losses. Next-generation environmental scientists and engineers will be trained at the graduate, postdoctoral, and undergraduate levels. Science videos about erosion will be created and disseminated to the public. Demonstration experiments will be used to raise K-12 students’ interest in environmental science and public understanding of erosion. This study will combine multiscale experiments and numerical simulations to understand the fundamental physical factors governing cohesive sediment transport. The study will directly address key challenges related to the multiscale and multiphysics nature of cohesive sediment transport dynamics that currently inhibit understanding of these processes. This includes the fact that transport that occurs at channel and ecosystem scales is controlled by the micro- to mesoscale interactions between nanometer-size clay particles, which are the main contributors to sediment cohesiveness, and by the multiphysics couplings between particle mechanics and fluid flow. The planned research will combine nano- to microscale confocal imaging and coarse-grained molecular dynamics (CGMD) simulations, micro- to mesoscale millifluidic experiments and computational fluid dynamics (CFD) simulations, and channel scale flume and outdoor stream experiments and CFD simulations to fundamentally understand the critical impacts of clay aggregation and gelation on channel-scale cohesive sediment transport.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

每年，美国因侵蚀而损失数十亿美元的财产和大片栖息地，为了减轻与侵蚀相关的损害和栖息地丧失，恢复项目将沉积物输入到侵蚀地区，这些恢复工作的成功取决于它们保留的能力。沉积物，因此恢复设计需要充分了解沉积物的迁移，目前，已经建立了预测非粘性沉积物（例如沙子和砾石）相对于流动条件和沉积物颗粒尺寸的迁移的方法。预测粘性物质的运输沉积物，如粘土或泥土，在水生生态系统中普遍存在，由非常细的颗粒组成，因此预测粘性沉积物的运输具有挑战性，因为这些细颗粒具有强烈的粘在一起并形成聚集体的倾向，这些聚集体极大地改变了沉积物的有效尺寸。该项目将结合各种尺度的实验和数值模拟，以了解细小的粘性颗粒如何形成聚集体以及聚集如何控制水中沉积物的传输。这项研究的损失结果将有助于改进修复项目的设计，以减轻侵蚀驱动的财产和栖息地。下一代环境科学家和工程师将接受研究生、博士后和本科生的培训。将制作并向公众传播有关侵蚀的科学视频，以提高 K-12 学生对环境科学的兴趣和公众对侵蚀的理解。控制因素该研究将直接解决与粘性沉积物输运动力学的多尺度和多物理性质相关的关键挑战，这些挑战目前阻碍了对这些过程的理解，这包括发生在河道和生态系统尺度上的输运是由微观因素控制的。纳米级粘土颗粒之间的介观相互作用（这是沉积物粘性的主要贡献者），以及颗粒力学和流体流动之间的多物理场耦合，计划的研究将结合纳米到微米级共焦成像。和粗粒度分子动力学 (CGMD) 模拟、微观到中尺度微流体实验和计算流体动力学 (CFD) 模拟、渠道规模水槽和室外流实验和 CFD 模拟，从根本上了解粘土聚集和凝胶对渠道的关键影响该奖项反映了 NSF 的法定使命，并通过使用基金会的智力价值和更广泛的影响审查标准进行评估，被认为值得支持。