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

美国国家海洋和大气管理局估计，地方、州和联邦政府在维护现有海滩的营养项目上的大量财政投资，仅通过旅游收入就能获得10倍的回报。随着海平面上升和人口对海岸线的需求增加，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上升。这些工程一般都能成功地暂时恢复海滩的宽度，但重新滋养的沉积物比“原生”沉积物具有不同的特征，因此更容易被侵蚀。pi将为这些研究制定一个实验计划。泥沙运动的理论在很大程度上忽略了通过的波浪或更局部的湍流扰动的非定常贡献。基于这些原理的现有应用工程模型在预测中等波浪气候（例如3-5秒的小波周期和大约1米的波高）中泥沙的陆上运输时，具有相对较低的技能，平均流量弱，海滩重建，并且可以显著受益于对近岸泥沙动力学的改进理解。PI试图验证的假设是，在波浪驱动的海岸环境中，水流不稳定，沉积物特征可能是非均质的，沉积物床的初始运动是剪切应力梯度和水平压力梯度共同作用的结果。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发展随机自由表面重力波响应下泥沙初期运动的理论公式，扩展Sleath 1999年的公式；开发智能沉积物颗粒（SSG）来测量单个颗粒（或颗粒）的三维加速度；最后通过全面的全尺寸实验室观测，观察非均质沉积物（天然颗粒和智能颗粒）的运动和输运。全面观测将在伊利诺伊大学（UIUC）的Ven Te Chow实验室进行。将获得一系列天然颗粒类（0.2至50毫米至20.0毫米）的观测数据，也将获得一系列较轻颗粒的观测数据，以便获得与沿海环境相关的全参数空间范围。这项工作代表了无线技术专家和沉积物运输科学家之间的协同合作。这项工作在应用最先进的MEMs技术方面具有变革性，可以解决长期存在的关于暴露在自由表面重力波下间歇性移动沉积物床运动的基本问题。这一努力存在着广泛而广泛的影响，包括增加代表性不足群体的参与，将高科技转化为社会，培养k-12学生进入科学和工程领域，以及提高沿海管理模型的预测技能。本项目将为一名少数民族女学生的博士研究提供支持。这些pi将参加UNH的Joan and James Leitzel中心的外展计划，并通过Girls Inc， Eureka！与TUDelft的持续合作将为将科学发现转化为更大的工程界提供成功的荷兰方法建模的机会。

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.