風洞床面の粗度の変化による気流の性状について(その2)

Abstract

In an effort to improve the understanding of wind flow in an urban environment, windtunnel simulations were carried out using an urban model of 1/250 scale. The results fromthese simulations were compared with those derived from tests based upon the moderately roughsurface flow generated by the uniformly distributed artificial grasses in the previous paper.The results show that the boundary layer thickness increases with the fetch above both theurban model and the artificial grasses. Close to the ground surface, there is a layer in whichmean wind speed and turbulence intensity distributions vary with the surface roughness andthe fetch. In the case of the urban model, the lower layer occupies almost the half of the bound-ary layer. But in the case of the artificial grasses it occupies less than thirty percent. In theupper and lower layers of both cases, the distributions of the mean wind speed can be determinedby graphing their respective logarithmic curves.