The wind field and pollutant dispersion are predicted numerically in a local urban area with crowded buildings and heavy traffic.A domain decomposition method is used in the large eddy simulation,in which the urban area is decomposed into a central area,where pollution is the major concern,and a surrounding region,where the pollutant distribution is not important.The composite model is proposed for the complex building-street layout.The fine grid mesh is used to resolve the buildings in the central area while the buildings are treated as roughness elements in the surrounding region where the coarse grids are used.The proposed numerical method is applied to simulate the wind field and pollutant dispersion from vehicle exhaust in the Rua Do Campo area of Macao.The results show that the composite model is an appropriate method for predicting wind field and pollutant dispersion in the crowded building area.
LIU YuShiCUI GuiXiangWANG ZhiShiHUANG WeiXiXU ChunXiaoZHANG ZhaoShun
We investigates the effect of Taylor-Grtler vortex on the Reynolds stress transport in the rotating turbulent channel flow by direct numerical simulation. The Taylor-Grtler vortex is detected by longitudinal average of velocity fluctuation in the channel and defined as TG fluctuation. It has been found that turbulent diffusion is significant in the Reynolds stress transportation at the suction side of rotating turbulent channel in contrast with the turbulent channel flow without rotation and Taylor-Grtler vortex plays an important role in the turbulent diffusion in Reynolds stress transport. The paper focuses on the low and moderate rotation number, but the effect of the rotation number on the Reynolds stress transport is also reported.
YANG ZiXuan 1 , CUI GuiXiang 1 , XU ChunXiao 1 , SHAO Liang 2 & ZHANG ZhaoShun 1 1 Department of Engineering Mechanics, Tsinghua University, Beijing 100084, China
