树冠特征对城市街谷内流场及污染物扩散影响的数值模拟研究

In this paper, a stochastic algorithm is established to characterize the complex distribution of leaves in the canopy, and a tree-wind-pollutant coupling mathematical model is proposed. The effects of canopy porosity and location on flow field and pollutant concentration field in street canyon (height: width = 1: 2) were studied by numerical simulation. It is found that when the tree crown is located in the middle of the street canyon, the street canyon is controlled by a flat dominant vortex, the change of porosity does not significantly affect the pollutant concentration distribution in the street canyon, but weakens the average velocity in the street canyon. When the tree crown is close to the windward side, the vortex center moves to the middle of the street canyon, and the average velocity in the street canyon is the lowest, which is 0.833m/s, which is about 8.4% lower than that without trees; the pollutant concentration in the bottom and leeward side of the street canyon is significantly higher than that in the middle and leeward side of the street canyon. This study is expected to provide reference and guidance for the selection and layout of tree planting types in streets.