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: 2150797
• 负责人: Ian Bourg
• 金额: $ 30.61万
• 依托单位: Princeton University
• 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=2150797&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，美国都会因水土流失而损失数十亿美元的财产和大片栖息地。为了减少与侵蚀相关的破坏和栖息地的损失，修复项目向被侵蚀地区输入沉积物。这些修复工作的成功取决于它们保留泥沙的能力，因此修复设计需要对泥沙运输有很好的了解。目前，已建立了与水流条件和泥沙颗粒大小相关的非粘性泥沙(如砂和砾石)输移的预测方法。然而，粘性泥沙，如粘土或泥沙，在水生态系统中普遍存在，并且由非常细的颗粒组成，因此预测粘性泥沙的迁移仍然是困难的。预测粘性泥沙输运是具有挑战性的，因为这些细小颗粒有强烈的粘在一起并形成集合体的趋势。这些集合体极大地改变了泥沙颗粒的有效尺寸及其与水流的相互作用。该项目将在一系列尺度上结合实验和数值模拟，以了解细小的粘性颗粒如何形成聚集体，以及聚集体如何控制沉积物在水中的传输。建立粘性泥沙输移的预报方程。这项研究的结果将有助于改进修复项目的设计，以减少因侵蚀而造成的财产和栖息地损失。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。将制作有关侵蚀的科学视频，并向公众传播。将利用演示实验来提高K-12学生对环境科学的兴趣和公众对侵蚀的了解。这项研究将结合多尺度试验和数值模拟来了解控制粘性泥沙运动的基本物理因素。这项研究将直接解决与粘性泥沙输运动力学的多尺度和多物理性质有关的关键挑战，目前粘性沉积物输运动力学阻碍了对这些过程的理解。这包括以下事实：发生在河道和生态系统尺度上的迁移由纳米粘土颗粒之间的微尺度到中尺度的相互作用以及颗粒力学和流体流动之间的多物理耦合控制，纳米粘土颗粒是沉积物粘性的主要贡献者。这项计划中的研究将结合纳米到微米尺度的共焦成像和粗粒度分子动力学(CGMD)模拟、微观到中尺度的微流体实验和计算流体动力学(CFD)模拟，以及河道尺度的水槽和室外河流实验以及CFD模拟，以从根本上了解粘土聚集和凝胶化对河道尺度粘性泥沙输送的关键影响。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。