Collaborative Research: Combined Waves and Currents over Multi-Scale Topography: From Boundary Layer Dynamics to Parameterization

合作研究：多尺度地形上的组合波和流：从边界层动力学到参数化

基本信息

批准号：
2123708
负责人：
James Hench
金额：
$ 10.03万
依托单位：
Duke 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：
2021-09-01 至 2024-08-31
项目状态：
已结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=2123708&HistoricalAwards=false
关键词：
Collaborative Research Combined Waves Currents

项目摘要

Multiscale bottom topography is ubiquitous in coastal systems. Interactions of surface waves and currents with this topography cause spatial patterns in pressure, velocities, and turbulence production that result in bottom drag, drive mixing, and dissipate wave energy. In most wave and circulation studies these processes are not resolved and are represented in bulk friction parameters, typically derived empirically. Dynamics of wavy flows over multiscale topography are not well understood and there is currently no method for computing friction parameters for waves and currents a priori from multiscale topography properties. This project will examine interactions of surface waves and currents with multiscale bottom topography, to investigate the controlling dynamics and develop appropriate bottom friction parameterization schemes, using modeling of flow over idealized and natural coral reef topography together with theoretical development. Implications for drag, wave dissipation and mixing will be addressed yielding improved understanding and modeling of reefs and similar systems. The project will inform interdisciplinary coral reef work through the PIs’ involvement with the Moorea Coral Reef LTER, and support an early career PI, a post-doc and a PhD student, and provide six undergraduates with research experiences. The project team will also develop and implement new K-12 outreach and education activities. In previous work, the PIs investigated boundary layer dynamics over topography characterized by a single length scale across a parameter range typical of reefs. Those results, along with analyses of reef topography, show that a range of topography length scales (cm - m) are likely to contribute substantially to bottom friction. This project will investigate how different topography length scales act together in multiscale topography to determine dynamics of the combined current and oscillatory flow, total drag on currents, and dissipation of wave energy. Using dynamical regimes for single-scale topography as a guide, the work will investigate the physics of combined waves and currents over multiscale topographies spanning different regimes (inertia-, drag-, stress-dominated) by conducting a series of computational fluid dynamics simulations in which key parameters (wave properties, current, topography length scales scaling properties) are systematically varied. Simulations will include topographies composed of superposed discrete length scales, surfaces with a continuous range of length scales, and reef topographies. Simulations (using OpenFOAM with LES closure) will resolve flow patterns down to roughness element scales. A spatially- and wave- ensemble-averaged Navier-Stokes framework will be applied to simulation results to analyze effects of roughness-element-scale processes on oscillatory and steady flow dynamics, and mechanisms by which energy is lost from waves and current will be quantified. These analyses will form the basis for new parameterizations for wave dissipation and drag on currents over multiscale topography that represent smaller-scale dynamics and can be incorporated into wave and circulation models.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.

多尺度的底形图在沿海系统中无处不在。表面波和电流与该地形的相互作用会导致压力，速度和湍流产生的空间模式，从而导致底部阻力，驱动混合和消散波浪能。在大多数波浪和循环研究中，这些过程尚未解决，并以散装摩擦参数表示，通常是经验得出的。多尺寸地形上波浪流的动力学尚不清楚，目前尚无对波和电流计算摩擦参数的方法。该项目将使用多尺度的底层形象研究表面波和电流的相互作用，以研究控制动力学并开发适当的底部摩擦参数化方案，并使用在理想化和自然珊瑚礁地形上进行流程的建模以及理论发展。对阻力，波浪耗散和混合的影响将得到解决，从而提高对珊瑚礁和类似系统的理解和建模。该项目将通过PIS与Moorea Coral Reef lter的参与来为跨学科的珊瑚礁工作提供信息，并支持早期的职业生涯PI，DOS DOC和PHD学生，并为六名本科生提供研究经验。项目团队还将开发和实施新的K-12外展和教育活动。在先前的工作中，PI研究了边界层动力学，而不是跨越礁石的参数范围内的单个长度尺度的特征。这些结果以及对礁石地形的分析表明，一系列地形长度尺度（CM -M）可能对底部摩擦有很大贡献。该项目将研究不同的地形长度尺度如何在多尺度地形中一起起作用，以确定组合电流和振荡流的动力学，电流的总阻力以及波能的耗散。使用动态的单尺度地形作为指导，这项工作将通过进行多个机制（惯性，拖动，压力为主）的多尺度地形上的合并波和电流的物理，通过进行一系列计算流体动力学模拟，其中一系列关键参数（波属性，当前，地形，地形长度尺度尺度尺度尺度）是系统的。仿真将包括由超级离散长度尺度，长度范围范围连续的表面和礁石地形组成的地形。仿真（使用带有LES闭合的OpenFOAM）将流量模式降低到粗糙度元素尺度。在空间和波集成的Navier-Stokes框架上，将应用于模拟结果，以分析粗糙度元素尺度过程对振荡和稳定流动动力学的影响，以及从波和电流中损失的能量的机制将被量化。这些分析将构成波浪耗散新参数的基础，并在多尺寸地形上拖动电流，这代表了较小的动力学，并可以将其纳入波浪和循环模型中。该奖项反映了NSF的法定任务，并被认为是通过基金会的知识分子优点和更广泛的影响审查标准来通过评估来通过评估来支持的。