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Review on Numerical Simulation of Airflow and Pollutant Dispersion in Urban Street Canyons under Natural Background Wind Condition

Category: Air Pollution Modeling

Volume: 18 | Issue: 3 | Pages: 780-789
DOI: 10.4209/aaqr.2017.09.0303
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Yunwei Zhang, Zhaolin Gu , Chuck Wah Yu

  • School of Human Settlements and Civil Engineering, Xi’an Jiaotong University, Xi’an 710049, China


Airflow and pollutant dispersion in urban street canyons are reviewed.
Effects of natural/time-varying wind conditions are summed up.
Perspectives on performing the time-varying inflow conditions are provided.


Observation data show that natural wind has a characteristic of regular time-variation in speed and direction. However, the time-varying inflow conditions are usually simplified as a constant wind profile in simulations on airflow and pollutant dispersion in urban street canyons and/or building cluster. The study on characteristics of urban canopy layer (UCL) flow under time-varying inflow conditions should be further contribute to the understanding of pollutant and energy transport processes in the urban atmospheric environment. In the current work, typical studies on air flow and pollutant dispersion in urban street canyons and building array are reviewed. The time-varying upstream inflows could commonly enhance the transportation of pollutant and energy in actual UCL. Studies have revealed that the variation of natural inflow conditions could be one of the primary factors that influencing the transport efficiency of pollutant in urban street canyons. Perspectives on methods in performing the time-varying inflow conditions are provided as well. Gradual and/or stepped variation of wind data would be expected in numerical simulations.


Pollutant dispersion Natural wind condition Urban street canyon Gusty wind Time-varying inflow

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