LES analysis on the temporal-spatial structures of gust wind over complex terrain by using the wind turbulence simulator.

在地形尖锐复杂的情况下，我们经常会遇到由于地表起伏的大变形或风流分离而产生的极高风。这会对建筑物和结构物造成破坏，因此，弄清复杂地形上的强风特性并估计设计风速的放大系数对于减轻其影响至关重要。然而，迄今为止，强风的估计仅限于相对简单的地形配置。考虑到实际地形的复杂性，数值方法预测地形对风场的影响比风场实验方法更有希望，因为风场实验方法需要花费大量的精力来单独制作地形模型。由于强风在时间和空间上都有很大的波动，为了确定建筑物和结构物在强风下的结构安全性，需要估计瞬时阵风最大值和平均风速。本文发展了适用于复杂地形强风的大涡模拟（LES）非定常计算技术，研究了近地层阵风的时空结构。特别着重讨论了来流和不同粗糙度下的湍流特性及其对强风的影响。

In case that the terrain is sharp and complicated, we often encounter the extremely high wind generated as a result of large deformation or separation of wind flows over undulation of ground surface. This causes damage to buildings and structures, so it is important for its mitigation to clarify strong wind characteristics over a complex terrain and estimate amplification factors of the design wind velocity. However the estimation of strong wind has been thus far limited to a relatively simple configuration of terrain. Taking into consideration complexity of actual terrain, the numerical technique is very expecting to predict the terrain effect on wind flows, compared to the wind experimental technique which requires a lot of efforts to make a terrain model individually. For the establishment of structural safety for buildings and structures to strong wind, it is required to estimate the instantaneous gust maximum as well as the averaged velocity for wind because this kind of wind has very large fluctuations in time and space. This study developed the unsteady computational technique of LES(Large eddy simulation) in the generalized coordinate system as a numerical turbulence model appropriate to strong wind over complex terrain and investigated the temporal-spatial structures of gust wind in the atmospheric surface layer. Especially we bring into focus the turbulence characteristics in the oncoming wind flows or over various types of surface roughness, and their effects on the strong wind are discussed.