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| Simulation of three-dimensional fluctuating wind velocity field #br# upon thunderstorm downburst |
| LOU Wen-juan, WANG Jia-wei, YANG Lun, CHEN Yong |
| Institute of Structural Engineering, Zhejiang University, Hangzhou 310058, China |
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Abstract Based upon the impinging jet model, the results of Reynolds stress calculated by Reynolds stress model (RSM) were introduced into the spectrum functions proposed by Letchford and Panofsky respectively. With the three-dimensional fluctuating wind velocity field of the thunderstorm downburst obtained from large eddy simulation (LES), both spectrums were validated, and the one which differs a lot was further revised. In combination with random flow generation technique and fast Fourier transform technique, an efficient method for the simulation of three-dimensional fluctuating wind velocity of the thunderstorm downburst was developed, which satisfied the incompressible condition and coherence function. In order to verify its accuracy, some typical points in a specific radial area of the downburst wind field with relatively high horizontal radial wind velocities were chosen. The simulation method mentioned above was employed to get the three-dimensional fluctuating wind velocities point-by-point along the height direction, whose auto-power spectrum functions and time coherence functions were further checked. The results match well with the target values, which implies that the method can simulate the three-dimensional fluctuating wind velocity field of downburst efficiently and precisely．
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Published: 04 August 2014
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雷暴风三维脉动风速场数值模拟
基于壁面射流模型,将雷诺应力模型（RSM）计算得出的Reynolds应力张量引入Letchford谱和Panofsky谱,利用大涡模拟（LES）计算得出的脉动风速结果对其进行验算.对偏差较大的风谱函数进行进一步修正,得到与LES计算结果较吻合的自功率谱函数.结合随机流场生成技术和快速傅里叶变换技术,提出满足不可压缩条件和点相干函数的适用于雷暴风三维脉动风速场的高效的数值模拟方法.为了验证该方法的合理性,选取流场中水平径向风速较大处在高度方向上逐点生成三维脉动风速,对每个点的模拟结果从自功率谱函数和时间相关函数两方面进行验证.模拟值与目标值的吻合效果良好,说明采用提出的方法可以高效、准确地模拟出雷暴风的三维脉动风场.
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