Abstract：An Eulerian-Lagrangian method was further developed to simulate the moving vehicles induced air flows within urban street canyons. In the Lagrangian scheme, each vehicle was tracked and the vehicle induced drag forces on the surrounding air are formulated. Under different background wind velocities, the simulations show that, moving vehicles have much effect on wind turbulences, yet less effect on the average wind field within the street canyon. The presence of vehicle induced turbulences is near the ground, and the induced turbulence adrift near the leeward wall is larger than that in other areas within the street canyon. The vehicle induced turbulence under different background wind velocity in urban street canyons is hard to be parameterized by the vehicle speed or the ratio of vehicle speed over background wind velocity.

Keywords：urban street canyon; turbulent flow; wind field; numerical simulation; Lagrangian scheme