Direct Phase-Resolved Simulation of Wind-Waves

知识价值：风浪问题是物理海洋学和流体力学中的一个经典课题，具有许多重要应用。本研究的目的是发展一种波浪相位分辨的数值模拟能力，用于模拟中等海况下的风浪，研究风浪之间的相互作用，有效地捕捉波浪模拟中波浪破碎耗散的影响，并进行基于模拟的风浪动态演化研究。该研究旨在建立一个基于物理的风浪精细分辨率模拟框架，可用于理论，数值和实验研究，用于模型开发和交叉比较。模拟建立在一套先进的数值方法基础上，包括非线性波的高阶谱方法（HOSM），大涡模拟（LES）与先进的亚网格尺度（SGS）模型的风湍流的边界拟合网格，遵循波浪运动，并作为一种辅助工具，陡波和破碎波的混合多流体模拟方法。风模拟将与波浪模拟动态耦合，具有双向交互作用。根据HOSM模拟，波场将为风LES提供真实的底部边界条件。使用一个新的动态SGS海面粗糙度模式，短期重力波对风的影响将模拟没有特设的调整模型系数。反过来，风LES将为波浪的HOSM模拟提供风强迫。使用波浪破碎模型（将使用陡波和破碎波的辅助HMFS进行评估和校准），在HOSM中还将考虑波浪破碎耗散。因此，风输入，非线性波浪相互作用和波浪破碎耗散的过程都将被纳入波场的相位分辨模拟的第一次。本项目计划进行系统的试验和与其他研究的广泛比较，其中一些计算方法，如采用动态SGS海面粗糙度模型的动态演变非线性波场的风大涡模拟、直接风输入的非线性波场的相分辨模拟和波浪破碎耗散的模拟、陡波和破碎风浪的模拟等，都是同类研究中的首创。这项研究将产生详细的数据，相互作用的风和波场的波相分辨的背景下，这可以揭示新的光的长期存在的问题，风浪动力学。本文的研究结果将有助于与实验测量和理论分析的比较。模拟数据也将有助于改进模型的开发，用于大规模波相平均模拟。更广泛的影响：这项研究的主题是科学界以及公众感兴趣的。拟议的研究将提高模拟能力和对风浪的理解，这对许多应用至关重要，包括天气和气候变化，船舶和海上结构的操作和安全，可再生能源和污染物运输。在该项目中，博士研究生教育将强调多学科培训，重点是波浪和湍流问题的计算。研究生招聘和指导将利用NSF IGERT项目对授予JHU的复杂系统进行建模。IGERT项目强调为国内博士生，特别是代表性不足的少数民族，妇女和第一代学生提供多尺度多物理问题的高性能计算培训。JHU的教育推广中心将促进教育推广，PI将通过该中心与当地巴尔的摩高中合作，使高中生，特别是来自服务不足社区的高中生，接触大学研究，并激励他们追求高等教育和科学工程职业。

Intellectual merit: The wind-wave problem is a classic subject in physical oceanography and fluid mechanics with many important applications. The objective of this study is to develop a wave-phase-resolved numerical capability for the simulation of wind-waves under moderate sea conditions, to investigate the interaction between the wind and waves, to effectively capture the effect of wave breaking dissipation in the wave simulation, and to perform simulation-based study of the dynamic evolution of wind-waves. The study aims at establishing a framework for physics-based fine-resolution simulation of wind-waves that can be used by theoretical, numerical, and experimental studies for model development and cross comparison.The simulation builds on a suite of advanced numerical methods including a high-order spectral method (HOSM) for nonlinear waves, large-eddy simulation (LES) with advanced subgrid-scale (SGS) models for wind turbulence on boundary-fitted grid that follows the wave motion, and, as an auxiliary tool, a hybrid multi-fluid simulation (HMFS) method for steep and breaking waves. The wind simulation will be dynamically coupled with the wave simulation with two-way interactions. From the HOSM simulation, the wave field will provide a realistic bottom boundary condition for the wind LES. Using a new dynamic SGS sea-surface roughness model, the effect of short gravity waves on the wind will be modeled without ad hoc tuning of the model coefficient. In return, the wind LES will provide wind forcing for the HOSM simulation of the waves. Using wave breaking models, which will be assessed and calibrated with the auxiliary HMFS of steep and breaking waves, wave breaking dissipation will also be taken into account in the HOSM. As such, the processes of wind input, nonlinear wave interaction, and wave breaking dissipation will all be incorporated to the phase-resolved simulation of the wave field for the first time. Systematic tests and extensive comparisons with other studies are planned in the proposed project.Some of the proposed computations, such as the wind LES over dynamically-evolving nonlinear wave field with dynamic SGS sea-surface roughness modeling, the phase-resolved simulation of nonlinear wave field with direct wind input and modeling of wave breaking dissipation, and the simulation of steep and breaking wind-waves, are the first of their kind. This study will produce detailed data of the interacting wind and wave fields in a wave-phase-resolved context, which can shed new light on the long- standing problem of wind-wave dynamics. The results of the proposed research will be useful for the comparison with experiment measurement and theoretical analysis. The simulation data will also be helpful for the development of improved models for large-scale wave-phase-averaged simulations.Broader impacts: The topic of this study is of interest to the scientific community as well as the general public. The proposed study will lead to improved simulation capability and understanding of wind-waves, which are essential to many applications including weather and climate change, operation and safety of ships and offshore structures, renewable energy, and pollutant transport. In the project, doctoral graduate education will stress multi-disciplinary training with a focus on computation of wave and turbulence problems. Graduate student recruiting and mentoring will leverage an NSF IGERT project on modeling complex systems awarded to JHU. The IGERT project places emphasis on training in high-performance computation of multi-scale multi-physics problems for domestic doctoral students, especially under-represented minorities, women, and first-generation students. Educational outreach will be facilitated by the Center for Educational Outreach at JHU, through which the PI will work with local Baltimore high schools to expose high school students, especially those from underserved communities, to university research and to inspire them to pursue higher education and careers in science and engineering.