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

据美国国家海洋和大气管理局估计，仅通过旅游业的收入，地方、州和联邦在维护现有海滩的营养项目上的大量财政投资就得到了十倍的回报。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的社会经济和生态压力也将上升。这些项目一般都能成功地暂时恢复海滩宽度，但重新滋养的沉积物侵蚀得更快，因为它具有与“原生”沉积物不同的特性。PI将为这些研究制定实验计划。泥沙运动的理论在很大程度上忽略了来自过往波浪或更局部的湍流扰动的任何不稳定贡献。现有的应用工程模型的基础上，这些原则有相对较低的技能时，预测陆上运输的沉积物在中等波浪气候（例如，3-5秒的小波浪周期和波高约1米）与弱的平均流量，海滩重建，可以显着受益于近岸沉积物动力学的理解。PI试图检验的假设是，在波浪驱动的海岸环境中，水流状态是不稳定的，沉积物特性可能是不均匀的，沉积物床的初始运动是由剪切应力梯度和水平压力梯度的组合引起的。PI将通过开发一种新的无线拉格朗日传感器来测试这一假设，智能沉积颗粒。该项目的具体目标是：扩展Sleath 1999年的公式，建立随机自由表面重力波作用下泥沙起动的理论公式;开发智能泥沙颗粒（SSG），测量单个微粒的三维加速度（或颗粒）;最后通过全面的全尺寸实验室观测，观察异质沉积物（天然颗粒和智能颗粒）的运动和输运。将在伊利诺伊大学（UIUC）的Ven Te Chow实验室进行全尺寸观察。观测将获得一系列的天然颗粒类（0.2 d50 - 20.0 mm），也为一系列较轻的颗粒，这将允许一系列的完整的参数空间相关的沿海环境。这项工作是无线技术专家和沉积物运输科学家之间的协同合作。这项工作是变革性的，在其应用国家的最先进的MEMS技术，以解决长期存在的基本问题，间歇性移动的沉积物床暴露于自由表面重力波的运动。这一努力存在着广泛的影响，包括增加代表性不足的群体的参与，将高科技转变为社会，将k-12学生带入科学和工程，以及提高沿海管理模型的预测能力。该项目将为博士学位提供支持。少数民族女学生的研究。PI将参加在琼和詹姆斯Leitzel中心在UNH和通过女孩公司，尤里卡外展计划！与TUDelft正在进行的合作将提供一个机会，以模拟成功的荷兰方法，将科学发现转移到更大的工程社区。

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.