Collaborative Research: LES and RANS simulations of estuarine flows: Understanding and parameterizing the role of Langmuir turbulence

合作研究：河口流的 LES 和 RANS 模拟：理解和参数化 Langmuir 湍流的作用

• 批准号: 1803335
• 负责人: Yuri Bazilevs
• 金额: $ 17.82万
• 依托单位: University of California-San Diego
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2018
• 资助国家: 美国
• 起止时间: 2018-08-15 至 2018-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1803335&HistoricalAwards=false
• 关键词: Collaborative; Research; LES; RANS; simulations

Langmuir circulation is recognized as pairs of parallel counter-rotating vortices (or cells) oriented approximately in the direction of the wind, characterizing the wave- and wind-driven turbulence (i.e. the Langmuir turbulence) within the upper ocean, lakes and estuaries. Its role in lakes and estuaries lacks understanding. The overarching goal of this project is to provide a fine-scale numerical study of Langmuir circulation, its interaction with other coherent flow structures and the resulting influence on vertical mixing and lateral dispersion within estuaries. Estuaries are briefly defined as coastal areas where freshwater and saltwater mix. Estuarine ecosystems are one of the most productive in the world made up of a myriad of habitats including oyster reefs, coral reefs, submerged aquatic vegetation, marshes and mangroves. The proposed numerical simulations will enhance understanding of flow dynamics that have direct impact on estuarine ecosystems. These dynamics govern the spatial distribution of water constituents such as dissolved organic matter, phytoplankton, suspended sediments and spilled contaminants that influence the health of estuarine ecosystems. The proposed studies consist of large-eddy simulations (LES) of the interaction between submesoscale coherent flow structures such as fronts and eddies and the smaller scale wind and wave-driven Langmuir circulation in idealized estuarine settings. LES will be used to investigate the idealized tidal intrusion front entering an estuary and an idealized river plume propagating through an estuary and discharging to a coastal ocean. The LES will allow investigations of (a) the role of turbulent mixing induced by Langmuir circulation in exchanges between the estuary and the coastal ocean via tidal intrusion fronts and river plumes and (b) the role of Langmuir circulation and its interaction with eddies and fronts determining the lateral and vertical mixing throughout the estuary. LES will allow for the development of improved turbulence closures able to account for the vertical mixing of the Langmuir turbulence regime. These closure models will then be used in Reynolds-averaged Navier-Stokes (RANS) simulations of the idealized flows and these results will be compared with the LES. This will allow for assessment of current turbulence closures for the RANS equations in the presence of Langmuir circulation. (3) Turbulence closures will be updated to account for Langmuir turbulence in RANS simulations. To date Langmuir turbulence closures have not been implemented for the three-dimensional RANS equations in coarse-scale estuarine flow simulations.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.

Langmuir循环被认为是沿风的方向大约面向的平行反向旋转涡旋（或细胞），表征了上海，湖泊和河口内的波和风驱动的湍流（即Langmuir湍流）。它在湖泊和河口中的作用缺乏理解。该项目的总体目标是提供对Langmuir循环的精细数值研究，与其他相干流结构的相互作用以及对河口内部河流混合和横向分散的影响。河口被短暂地定义为淡水和盐水混合的沿海地区。河口生态系统是世界上最有生产力的生态系统之一，由无数栖息地组成，包括牡蛎礁，珊瑚礁，淹没的水生植被，沼泽和芒果。提出的数值模拟将增强对对河口生态系统有直接影响的流动动力学的理解。这些动力学控制了水成分的空间分布，例如溶解有机物，浮游植物，悬浮沉积物和溢出的污染物，这些污染物会影响河口生态系统的健康。 所提出的研究包括在理想化的河口环境中的大涡模拟（LES），包括前镜相干流量结构（如前部和涡流）以及较小的尺度风和波驱动的Langmuir循环。 LES将用于调查理想化的潮汐入侵阵线，进入河口和理想化的河羽流，通过河口繁殖并排出沿海海洋。 LE将允许（a）通过潮汐入侵阵线和河流李子在河口和沿海海洋之间的交流中诱导的湍流混合的作用，以及（b）Langmuir循环的作用及其与涡流和前部的相互作用，以确定整个河口的涡流和垂直混合。 LES将允许开发改善的湍流封闭，以说明Langmuir湍流状态的垂直混合。然后，这些封闭模型将用于理想化流量的雷诺平均纳维尔 - 斯托克斯（RANS）模拟中，并将这些结果与LE进行比较。这将允许在存在Langmuir循环的情况下评估当前湍流封闭方程。 （3）将更新湍流封闭，以说明rans模拟中的langmuir湍流。迄今为止，尚未实施Langmuir湍流的封闭，用于在粗尺度的河口流量模拟中的三维票方方程。该奖项反映了NSF的法定任务，并且被认为值得通过基金会的知识分子优点和更广泛的影响标准通过评估来进行评估。