Collaborative Research: Experimental and Numerical Study of Bed Shear Stress and Turbulent Boundary Layer Structure Induced by Breaking-Wave-Generated Vortices

合作研究：破碎波产生涡流引起的床面剪应力和湍流边界层结构的实验和数值研究

• 批准号: 2049293
• 负责人: Francis Ting
• 金额: $ 30.07万
• 依托单位: South Dakota State University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2021
• 资助国家: 美国
• 起止时间: 2021-07-01 至 2025-06-30
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2049293&HistoricalAwards=false
• 关键词: Collaborative; Research; Experimental; Numerical; Study

This research aims to improve the understanding of breaking wave vortices impinging on the seabed. This has broad impacts on the prediction of a wide range of near-shore processes where wave breaking is fundamental in driving the sediment transport and resulting morphological changes. Detailed laboratory experiments will provide a high quality, comprehensive data set to test and improve a numerical model to better resolve the effects of wave breaking and eddy impingement on the bottom boundary layer structure. In return, the validated model will provide more detailed information to help interpret the measured data as well as a valuable research tool to model prototype wave conditions not reproducible in the laboratory. This research project would benefit society by enabling the development of better engineering tools for coastal zone management and mitigation of coastal hazards. The project will support two PhD students, one at South Dakota State University (SDSU) and another at the University of Delaware (UD), and will provide an opportunity for the new PhD program at SDSU to grow through research collaboration with an established research center. The PhD student from UD will participate in a portion of the experimental program at SDSU and work with the SDSU PhD student on model/data comparison. He/she will also work for a period at the University of Washington (UW) during the development of needed model extensions. To broaden the impacts of the research on STEM education, the lead PI will design a new technical elective on advanced fluid mechanics laboratory, which will be offered to undergraduate seniors and graduate students. The course will include a suite of experiments to give students hands-on experience with measuring bed shear stresses in steady and unsteady flows using different experimental techniques and approaches, emphasizing the importance of careful experimentation and analysis to produce high-quality, reproducible results.The objective of this research is to understand the structure of the bottom boundary layer and determine the bed shear stresses induced by the impact of breaking-wave-generated vortices on a plane beach. Laboratory experiments will be conducted in a 25 m-long, 0.9 m-wide and 0.75 m-deep tilting flume equipped with a programmable wave generator. The turbulent velocity fields under spilling and plunging waves will be measured in a three-dimensional (3D) flow volume on smooth and rough beds using a volumetric three-component velocimetry (V3V) system. The measured data will be used to study the momentum balance in the near-bed region and to develop more accurate methods for estimating the bed shear stresses in the unsteady, non-equilibrium boundary layer associated with breaking waves. The measured data will also be used to validate a multi-phase (air-water) large eddy simulation (LES) scheme for breaking waves, already shown to accurately describe the processes of wave breaking and eddy formation and evolution, to better resolve eddy impingement on the bottom and resulting modifications to the boundary layer structure.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.

这项研究旨在提高对撞击海床的断裂波涡流的理解。这对广泛的近岸过程的预测具有广泛的影响，在这些过程中，波浪破裂对于推动沉积物传输和导致形态学变化至关重要。详细的实验室实验将提供高质量的全面数据集，以测试和改进数值模型，以更好地解决波浪破裂和涡流撞击对底部边界层结构的影响。作为回报，经过验证的模型将提供更详细的信息，以帮助解释测得的数据以及有价值的研究工具，以模拟实验室不可重现的原型波条件。该研究项目将通过为沿海地区管理和减轻沿海危害的更好的工程工具开发而受益。该项目将支持两名博士学位学生，一名在南达科他州立大学（SDSU），另一个在特拉华大学（UD）支持，并将为SDSU的新博士学位课程提供一个机会，通过与既定研究中心的研究合作来成长。 UD的博士生将参加SDSU实验计划的一部分，并与SDSU PhD学生合作进行模型/数据比较。在开发所需模型扩展过程中，他/她还将在华盛顿大学（UW）工作一段时间。为了扩大研究对STEM教育的影响，PI领导者将设计一个有关高级流体力学实验室的新技术选修课，该专业人士将提供给本科生和研究生。 The course will include a suite of experiments to give students hands-on experience with measuring bed shear stresses in steady and unsteady flows using different experimental techniques and approaches, emphasizing the importance of careful experimentation and analysis to produce high-quality, reproducible results.The objective of this research is to understand the structure of the bottom boundary layer and determine the bed shear stresses induced by the impact of breaking-wave-generated vortices on a plane beach.实验室实验将以25 m长，0.9 m宽和0.75 m深的倾斜水槽进行，配备有可编程波发生器。溢出和跌落波下的湍流速度场将使用体积的三组分速度法（V3V）系统在光滑和粗糙的床上的三维（3D）流量中进行测量。测量的数据将用于研究近床区域中的动量平衡，并开发更准确的方法来估计与断裂波相关的不稳定，非平衡边界层中的床剪应力。测得的数据还将用于验证一个多相（空气水）大型涡流模拟（LES）方案，用于破坏波，已经显示出可以准确描述波浪破裂，涡形的形成和进化的过程，以更好地解决底部的涡流障碍，并通过对边界级的奖励进行了努力，以表现出nsf的Informition deem deem deem deem dee eyt of dee emportial deem deem dee eyt of dee eyt of dee ey teem dee ey tore tore te eem dee ey tore tee nsf of dee ey tore to eem dee emp and dee ey tore teem to nsf。更广泛的影响审查标准。

项目成果

Finding the Bed Shear Stress on a Rough Bed Using the Log Law

使用对数定律计算粗糙床上的床剪应力

• DOI: 10.1061/(asce)ww.1943-5460.0000707
• 发表时间: 2022
• 期刊: and Ocean Engineering
• 作者: Ting, Francis C.;Kern, Gunnar S.
• 通讯作者: Kern, Gunnar S.