A modeling of air flow in a street canyon

摘要

Steady plane-parallel isothermal turbulent flow of a viscous incompressible liquid above a surface with elements of a roughness is considered. Buildings and road with vehicle emissions form a city canyon. Reynolds equations and Bous-sinesq assumption are used to solve the considered problem. We apply the no-slip boundary conditions on the rigid walls, simple gradient conditions on the upper and outflow boundaries and known distributions of flow parameters on inflow boundary. Turbulent parameters are calculated on the basis of "k―ε" model of turbulence with near-wall functions approach for energy of turbulence k and dissipation ε. A numerical solution of the problem is found with,using of finite-volume method and the SIMPLE algorithm. Influence of atmospheric parameters on pollutant dispersion in a street canyon is investigated. Also influences of the geometrical factors of a city street canyon on a pattern of turbulent flow and distribution of harmful impurity concentration emitting from urban vehicles are investigated. The adverse meteorological situations resulting in accumulation of the harmful substances in street canyon are shown.