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Journal of Zhejiang University SCIENCE A

ISSN 1673-565X(Print), 1862-1775(Online), Monthly

Large eddy simulation study of 3D wind field in a complex mountainous area under different boundary conditions

Abstract: Large eddy simulations generally are used to predict 3D wind field characteristics in complex mountainous areas. Certain simulation boundary conditions, such as the height and length of the computational domain or the characteristics of inflow turbulence, can significantly impact the quality of predictions. In this study, we examined these boundary conditions within the context of the mountainous terrain around a long-span cable-stayed bridge using a wind tunnel experiment. Various sizes of computational domains and turbulent incoming wind velocities were used in large eddy simulations. The results show that when the height of the computational domain is five times greater than the height of the terrain model, there is minimal influence from the top wall on the wind field characteristics in this complex mountainous area. Expanding the length of the wake region of the computational domain has negligible effects on the wind fields. Turbulence in the inlet boundary reduces the length of the wake region on a leeward hill with a low slope, but has less impact on the mean wind velocity of steep hills.

Key words: Large eddy simulation (LES); Spectral representation method; Recycling method; High mountainous canyon; Wind characteristics; Atmospheric boundary layer; Computational domain

Chinese Summary  <15> 不同边界条件下复杂山区三维风场的大涡模拟研究

作者:李妍1,严磊1,2,3,何旭辉1,2,3
机构:1中南大学,土木工程学院,中国长沙,410075;2高速铁路建造技术国家工程研究中心,中国长沙,410075;3轨道交通工程结构防灾减灾湖南省重点实验室,中国长沙,410075
目的:探究利用大涡模拟研究山区桥址三维风场特征的适用性。研究计算域尺寸对模拟山区桥址风场特征的影响,并分析得出满足工程应用要求的最小计算域尺寸。研究大涡模拟中添加入口湍流的方法,并对比分析不同湍流入口条件对风场特征的影响。
创新点:1.设置了多种高度和长度的计算域进行计算和对比;2.研究了三种入口边界条件对风场特征的影响。
方法:1.使用大涡模拟计算与风洞试验设置完全一致的工况,验证大涡模拟的准确性;2.改变上述工况的计算域尺寸,并与之前的结果进行对比分析;3.分别使用谐波合成法和循环法生成入口边界的脉动风速序列,并将它们引入主计算域进行计算,对比分析两种湍流来流工况与均匀来流工况所得的桥址处风场特征。
结论:1.在山区风场的数值模拟中,计算域高度低于三倍模型高度时,顶部边界对风场影响很大;当计算域高度高于五倍模型高度时,顶部边界对风场影响微弱。2.计算域出口边界与桥址之间存在高山阻隔,故两者间距离对计算结果影响不大。3.入口边界的湍流特征对桥址处风剖面形状影响不大,但对桥址处湍流特征有明显影响;循环法产生的湍流入口边界能显著降低低空中的湍流强度。4.当地形坡度平缓时,入口湍流特征对后方风场影响较大,而当地形坡度陡峭时,入口湍流对后方风场影响较小。

关键词组:大涡模拟;谐波合成法;循环法;高山峡谷;风场特征;大气边界层;计算域


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DOI:

10.1631/jzus.A2300613

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On-line Access:

2024-08-27

Received:

2023-10-17

Revision Accepted:

2024-05-08

Crosschecked:

2024-07-24

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