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Influence of boundary inflow wind fluctuation on simulated urban atmospheric diffusion


Journal

China Environmental Science

Authors

Dong Long-xiang, Zuo Hong-chao, Yang Bin, Chen Ji-wei, Ma Kai-ming, Yu Ye

Year

2018

Volume

37

Issue

9

Pages

3210-3219

Corresponding Author

Zuo, HC

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zuohch@lzu.edu.cn

Keywords

urban diffusion neutral stratification CFD boundary condition numerical experiments

Abstract

The impact of the inflow wind fluctuation (i.e. wind velocity and wind speed) on the urban pollutant dispersion from a point source released at ground level under neutral stratification was analyzed using the computational fluid dynamics (CFD) model Fluent, where the boundary inflow conditions were provided in the form of wind velocity and turbulence profiles. Results suggested that the CFD model could reproduce the characteristic flow pattern (e.g. vortex, channeling, and so on) observed in actual urban environment, and the simulated wind velocity, wind direction and turbulence kinetic energy were in good agreement with observations. The results from a set of sensitivity experiments showed that the flow field and turbulent kinetic energy as well as the spatial distribution of pollutants in the urban area were very sensitive to the fluctuation of inflow wind speed and wind direction. This may be one of the main reasons for the inconsistency between the observed and the simulated concentrations in previous studies. Therefore, the uncertainty of boundary inflow should be considered in future simulation studies on urban atmospheric diffusion.