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

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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.