Large Eddy Simulations of Pollutant Dispersion in a Street Canyon

Abstract

Flow structure and pollutant dispersion in a 3D symmetric street canyon are numerically investigated using a computational fluid dynamics (CFD) model. The analyzed parameter is Reynolds number. The studied canyons is regular canyon with aspect ratio equal to one. The Reynolds number used are 9000, 14200, 19200 and 30700 where the free stream velocity are 0.68m/s, 1.07m/s, 1.45m/s and 2.32 m/s. Transport equation for CO and air is included and is assumed as non-reactive. The source of pollutant emission is assumed only from vehicular fumes situated at ground level. The best meshing size used in this simulation is 547050 which is used to run this simulation using large eddy simulation (LES). Vortex's pattern and strength are dependent of velocity at the roof level. Analysis on
the pollutant concentration shows that high Reynolds number will give the best air ventilation for street canyon subsequently decreased the pollutant concentration level.