基于大涡模拟的轻型柴油车尾流结构与污染物扩散研究.pdf

ARTICLE IN PRESS Atmospheric Environment 40 (2006) 1104–1116 /locate/atmosenv Large eddy simulation of flow structures and pollutant dispersion in the near-wake region of a light-duty diesel vehicle G. Dong, T.L. Chan Research Centre for Combustion and Pollution Control, Department of Mechanical Engineering, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong Received 19 May 2005; received in revised form 21 October 2005; accepted 1 November 2005 Abstract A three-dimensional large eddy simulation (LES) of flow structures and pollutant dispersion in the near-wake region of a light-duty diesel vehicle for both high and low idling conditions within the urban road microenvironments was performed. Four different grid resolutions with and without coordinate transformation were used for evaluating the grid independence on computational results of the LES approach. Time-averaged velocities, temperatures and pollutant concentrations along the centreline of the vehicular exhaust plume have been calculated for both high and low idling conditions. The computational results show that the finer grid cell provides a better agreement with the experimental results for both idling conditions. Furthermore, the computational work has been extended to investigate the effect of ambient wind conditions (i.e., wind speed and direction) on the flow dynamics and pollutant dispersion in the near-wake region of a light-duty diesel vehicle for high idling condition. For the low ambient wind speed case, the vehicular exhaust jet plume dominates the flow structures and the pollutant dispersion patterns. On the other hand, for