COLLABORATIVE RESEARCH: Smart Sediment Grains and the Incipient Motion of Coastal Heterogeneous Sediments

Foster/Chou0933409/0933694NOAA估计，地方、州和联邦政府为维护现有海滩而在营养项目上的巨额财政投资仅通过旅游收入就获得了十倍的回报。随着海平面上升和海岸线人口需求的增加，一些专家预测，海滩和沿海规划者面临的社会经济和生态压力也将增加。这些工程在暂时恢复海滩宽度方面通常是成功的，但重新滋养的沉积物侵蚀得更快，因为它具有不同于“本地”沉积物的特性。PIS将为这些研究开发和实验计划。泥沙运动理论在很大程度上忽略了通过波或更多局部湍流扰动对泥沙运动的非恒定贡献。基于这些原理的现有应用工程模型在预测中等波浪气候(如S的小浪周期为3-5个，波高约为1m)、海滩重建的弱平均气流中的泥沙输移时技能相对较低，并可从对近岸沉积物动力学的更好理解中受益匪浅。PI试图验证的假设是，在波浪驱动的海岸环境中，水流状况不稳定，泥沙特性可能是非均匀的，沉积物床的初始运动是剪应力梯度和水平压力梯度的组合。PI将通过开发一种新的无线拉格朗日传感器--智能沉积物颗粒来验证这一假设。该项目的具体目标是建立沉积物对自由表面随机重力波的初始运动的理论公式，扩展Sleath的1999年公式；开发一种智能沉积物颗粒(SSG)来测量单个微粒(或颗粒)的三维加速度；最后通过全面的全面实验室观察观察非均质沉积物(包括天然颗粒和智能颗粒)的运动和输送。伊利诺伊大学(UIUC)的周文德实验室将进行全面观测。将获得一系列自然颗粒级别(0.2 D50 20.0 mm)的观测，以及一系列较轻颗粒的观测，这些颗粒将允许与沿海环境相关的一系列完整参数空间。这项工作代表了一位无线技术专家和一位泥沙传输科学家之间的协同合作。这一努力在应用最先进的MEMS技术以解决暴露在自由表面重力波中的间歇移动沉淀层的长期基本问题方面具有变革性意义。这一努力产生了广泛而广泛的影响，包括增加代表性不足群体的参与，将高科技转化为社会，将K-12学生带入科学和工程领域，以及提高沿海管理模型的预测技能。该项目将为一名少数民族女学生的博士学习提供支持。PI将参加在UNH的Joan和James Leitzel中心以及通过Girls Inc，Eureka的外联计划！正在进行的与TUDelft的合作将提供一个机会，为将科学发现转移到更大的工程界的荷兰成功方法提供一个模型。

Foster/Chou0933409/0933694NOAA estimates that the large local, state, and federal financial investments in nourishment projects to maintain existing beaches is returned ten-fold through tourism dollars alone. As sea level rises and population demands on our shorelines increase, some experts predict the socioeconomic and ecological pressures on the beaches and coastal planners will also rise. These projects are generally successful at temporarily restoring the beach width, however re-nourished sediment more quickly erodes as it has different characteristics than the "native" sediment. The PIs will develop and experimental program for these studies. Theories for the motion of sediment largely neglect any unsteady contributions from the passing waves or more local turbulent disturbance. The existing applied engineering models based on such principles have relatively low skill when predicting the onshore transport of sediment in moderate wave climates (e.g small wave periods of 3-5 s and wave heights of roughly 1 m) with weak mean flows where beaches rebuild and could significantly benefit from an improved understanding of nearshore sediment dynamics. The hypothesis the PI's seek to test is that in wave-driven coastal environments where the flow regime is unsteady and the sediment characteristics can be heterogenous, the incipient motion of a sediment bed results from a combination of the shear stress gradient and the horizontal pressure gradient. The PIs will test this hypothesis by developing a new wireless Lagrangian sensor, the Smart Sediment Grain. The specific objectives for this project are to develop a theoretical formulation for the incipient motion of sediment in response to random free surface gravity waves, extending Sleath's 1999 formulation; develop a Smart Sediment Grain (SSG) to measure the three-dimensional acceleration of individual motes (or grains); and finally observe the motion and transport of heterogeneous sediments (both natural and smart particles) through a comprehensive full-scale laboratory observation. Full-scale observations will be performed at the Ven Te Chow Laboratory at the University of Illinois (UIUC). Observations will be obtained for a range of natural grain classes (0.2 d50 20.0 mm) and also for a range of lighter particles that will allow for a range of the full parameter space relevant to coastal environments. This effort represents a synergistic collaboration between a wireless technology expert and a sediment transport scientist. This effort is transformative in its application of state-of-the-art MEMs technology to resolve longstanding fundamental questions regarding the motion of intermittently mobile sediment beds exposed to free surface gravity waves. There exist wide-ranging broader impacts of this effort that include increasing the participation of underrepresented groups, transitioning high technology to society, entraining k-12 students into science and engineering, and increasing the predictive skill of coastal management models. This project will provide support for the Ph.D. studies of a minority female student. The PIs will participate in outreach programs at the Joan and James Leitzel Center at UNH and through Girls Inc, Eureka! Ongoing collaborations with TUDelft will provide an opportunity to model the successful Dutch methods for transitioning scientific findings to the larger engineering community.