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arXiv 2310.03350physics.flu-dyn
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非平稳飓风边界层风场的大涡模拟

Large Eddy Simulation of Non-stationary Hurricane Boundary Layer Winds

Tianqi Ma, Chao Sun, Paul Miller

AI总结:

针对极端飓风对基础设施的破坏问题,本文开发了考虑中尺度条件变化的大涡模拟飓风边界层模型,经两场飓风实测验证,该模型能准确捕捉风场与湍流特征,可用于民用基础设施的飓风风场模拟。

摘要:

近期极端热带气旋在全球范围内对关键民用基础设施造成了广泛破坏。为更好地捕捉飓风独特的风场特征,本文通过考虑中尺度运动学与热力学条件的变化,开发了一种大涡模拟(LES)飓风边界层(HBL)模型。模型采用非对称模式,利用美国国家飓风中心(National Hurricane Center)的数据获取梯度风速;中尺度热状况则通过从生成的替代探空数据中提取逐时气温与相对湿度廓线得到。研究采用哈维飓风(Hurricane Harvey)期间阿兰瑟斯县机场的观测数据,以及厄玛飓风(Irma)期间那不勒斯市的观测数据,对所开发的LES模型进行验证。结果表明,模拟得到的10分钟平均风速与风向和观测结果一致;该模型能较好地预测强风湍流,哈维飓风中湍流强度约为20%,厄玛飓风中约为26%。哈维飓风期间10米高度处的3秒阵风风速达62.4 m/s,厄玛飓风期间15米高度处达53.5 m/s,分别与现场观测的61.3 m/s和54.2 m/s接近。除部分因物理机制尚不明确导致变化显著的时刻外,模拟得到的3秒阵风系数与观测值接近;纵向与横向的模拟风谱也与观测结果吻合良好。综上,所开发的基于LES的HBL模型能够捕捉飓风结构与湍流的主要特征,可用于模拟受飓风影响的民用基础设施风荷载。

英文摘要:

Recent extreme tropical cyclones caused extensive damages to critical civil infrastructure globally. To better capture the unique hurricane wind characteristics, a large eddy simulation (LES) Hurricane Boundary Layer (HBL) model is developed by considering the variation of meso-scale kinematic and thermodynamic conditions. An asymmetric model is adopted to obtain the gradient wind velocity using the National Hurricane Center data. The meso-scale thermal conditions are obtained by extracting the hourly air temperature and relative humidity profiles from generated proxy soundings. Measurements recorded at the Aransas County airport during Hurricane Harvey and that at the City of Naples during Irma are used to validate the developed LES model. Research results show that the simulated 10-minute average wind speed and direction are consistent with the observations. The developed model can well predict the high wind turbulences, which are around 20% in Hurricane Harvey and 26% in Hurricane Irma. The 3-s gust wind speeds reach 62.4 m/s at 10-m elevation during Hurricane Harvey and 53.5 m/s at 15-m elevation during Hurricane Irma, close to the field observed data of 61.3 m/s and 54.2 m/s, respectively. The simulated 3-s gust factors are close to the observation except at some moments with significant variations because of the poorly understood physical phenomena. The simulated wind spectrum in longitudinal and lateral directions agrees well with the observed results. In summary, the developed LES-based HBL model can capture the main characteristics of hurricane structure and turbulence characteristics and is applicable for modeling civil infrastructure exposed to hurricanes.

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