Three-dimensional delayed detached-eddy simulation of wind flow and particle dispersion in the urban environment

Abstract

Recently, Haze-fog as an atmospheric phenomenon associated with high level of air pollutant has negative impacts on human health and environment, which arises the society attention. This paper is aimed at investigating the haze-fog dispersion in the urban environment from the physical view. The wind flow and particle dispersion in the urban environment are simulated by using the Delayed Detached-eddy Simulation (DDES) turbulence model and the Discrete Phase Model (DPM) under the atmospheric boundary layer flow. The results show that the particle dispersion is dominated by the wind flow including the velocity and vortex distribution and the gravity can slightly influence the particle deposition. The particle-empty areas around the buildings are identified during the dispersion and then they disappear gradually mainly through the recirculation function. When the wind direction changes, the blockage cross-section area derived from the building group becomes larger resulting in the larger low wind velocity area. Furthermore, the different reference inlet velocities directly affect the vorticity magnitude and the particle dispersion periods. It is concluded that the DDES model is a promising approach to simulate the haze-fog physical development in the urban environment.