In view of the pollution caused by the growing car ownership in China and the complex layout of urban traffic system, this paper uses computational fluid dynamics (CFD) to simulate the air speed distribution and concentration of vehicle exhaust pollutants in five typical street canyons, including rising type, descending type, concave type, convex type and horizontal type. The simulation reveals certain differences in vortex structure and air speed among the five canyons. Among them, the pollutants may diffuse into the upstream in descending and concave canyons, but only spread to the downstream in the other three canyons. The upstream buildings have a far greater impact on pollutant concentration than downstream buildings. At the heights of 1.6m and 10m, the rank of street canyons is descending > concave > rising > horizontal > convex in descending order in terms of the pollutant concentration.
computational fluid dynamics (CFD), street canyon, vortex, pollutant concentration
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