Abstract Flow conditions in complex terrains such as fjords are highly three-dimensional and thus not properly captured by the wind flow models developed for homogenous terrains. In the present study, we explore the potential of computational fluid dynamics (CFD) simulations relying on the steady 3D Reynolds-averaged Navier-Stokes equations to complement in-situ measurements from a long-span bridge in a narrow fjord. The validation is done using velocity data recorded in 2017 and 2018 by nine sonic anemometers mounted above the deck of a fjord-crossing suspension bridge. The flow characteristics studied are the along-bridge profile of the mean wind velocity, mean wind direction and mean angle of attack. The simulated flow shows that the non-uniform distributions of the mean angles of attack and wind direction along the bridge span are likely due to side-valley flows, which under certain conditions, predominate over those coming from the main valley. The measurements suggest that wind conditions corresponding to the dominating side-valley flows are associated with a high turbulence intensity at the bridge deck position. The paper highlights the complementary role of CFD studies and in-situ measurements for the design of a wind-sensitive structure, which may not be available using traditional semi-empirical modelling of topography effects.

中文翻译：

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地形对峡湾平均风流特性的影响

摘要 峡湾等复杂地形中的流动条件是高度三维的，因此为均匀地形开发的风流模型无法正确捕捉。在本研究中，我们探索了计算流体动力学 (CFD) 模拟的潜力，该模拟依赖于稳定的 3D 雷诺平均 Navier-Stokes 方程，以补充狭窄峡湾中大跨度桥梁的原位测量。验证是使用 2017 年和 2018 年由安装在跨峡湾悬索桥甲板上方的九个声速风速计记录的速度数据完成的。研究的流动特性是平均风速、平均风向和平均迎角的沿桥剖面。模拟流表明，平均攻角和风向沿桥跨的非均匀分布可能是由于侧谷流造成的，在某些条件下，侧谷流比来自主谷的流占主导地位。测量结果表明，对应于主要侧谷流的风况与桥面位置处的高湍流强度有关。该论文强调了 CFD 研究和原位测量在风敏结构设计中的互补作用，这可能无法使用传统的地形效应半经验建模。测量结果表明，对应于主要侧谷流的风况与桥面位置处的高湍流强度有关。该论文强调了 CFD 研究和原位测量在风敏结构设计中的互补作用，这可能无法使用传统的地形效应半经验建模。测量结果表明，对应于主要侧谷流的风况与桥面位置处的高湍流强度有关。该论文强调了 CFD 研究和原位测量在风敏结构设计中的互补作用，这可能无法使用传统的地形效应半经验建模。