Original paper

Dispersion of traffic exhausts emitted from a stationary line source versus individual moving cars – a numerical comparison

Gross, Günter

Meteorologische Zeitschrift Vol. 25 No. 4 (2016), p. 479 - 487

22 references

published: Sep 6, 2016
published online: Jul 6, 2016
manuscript accepted: Apr 18, 2016
manuscript revision received: Apr 17, 2016
manuscript revision requested: Apr 6, 2016
manuscript received: Mar 25, 2016

DOI: 10.1127/metz/2016/0797

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Abstract

A three-dimensional microscale model was used to study the effects of moving vehicles on air pollution in the close vicinity of a road. The numerical results are compared to general findings from wind tunnel experiments and field observations. It was found that the model is suitable to capture the main flow characteristics within an urban street canyon, in particular the modifications relating to running traffic. A comparison of the results for a stationary line source approach and for multiple single moving sources demonstrates significant differences. For a street in a flat terrain, the near-road concentrations are underestimated by up to a factor of two if the emissions are approximated by a stationary line source. This underestimation decreases with increasing distance, and becomes negligible 30–50 m away from the road. For an urban canyon situation, the line source assumption is a conservative approximation for the concentrations at the leeside of the street, while on the opposite pavement and wall, a systematic underestimation was found. Also, the effects of different traffic situations have been studied and discussed.

Keywords

Micro-scale simulationrunning trafficvehicle dispersionurban canyon concentration