Effects of inflow turbulence intensity on flow and pollutant dispersion in an urban street canyon

The effects of inflow turbulence intensity on flow and pollutant dispersion in an urban street canyon with a street aspect ratio of 1 are examined using a two-dimensional numerical model. As the inflow turbulence intensity increases, turbulent kinetic energy and turbulent diffusivity in the street canyon increases. Also, the mean horizontal velocity near the roof level increases and the street-canyon vortex strengthens. The analyses of the time series and residue ratio of pollutant concentration show that the inflow turbulence intensity significantly affects pollutant concentration in the street canyon. As the inflow turbulence intensity increases, the pollutant concentration in the street canyon becomes low and hence more pollutants escape from the street canyon.