Numerical simulation studies of the flow field and pollutant dispersion in the street canyon under different thermal stratifications

Abstract

This paper simulates the flow and dispersion in the street canyon under different thermal stratifications using three-dimensional (3-D) Computational Fluid Dynamics (CFD) methodology, and compares the simulated results with the wind-tunnel experiment data reported by Uehara et al. Monin-Obukhov length (L) is used to describe the atmospheric flow under different thermal stratifications. The results show that the effect of thermal stratification on the flow structure and pollutant dispersion within the street canyon is significant. The magnitude of velocity in the middle part of the street canyon is relatively small under different conditions. The intensity of vortex is significantly influenced by thermal stratification. The maximum value of k/U 700 2 appears near the windward corner of the building under different conditions. The high-concentration region appears in the upwind part of the canyon. The normalized concentration on the leeward side is greater than those of windward side within the street canyon under different conditions.