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Purposes The typical street canyon-building of the city is researched in this work. Methods On the basis of field measurement and numerical simulation CFD(Computational Fluid Dynamics), the airflow pattern and pollutant distribution in street canyon and indoor the building with windows opening were investigated. Findings The results show that the opening of windows on the outer wall of building disturbs the surrounding air flow, which leads to the enhancements of the vortex flow in the street canyon, and the variation of local wind direction and wind speed in different heights. The turbulence intensity of the street-facing buildings on the leeward side is more obviously affected by the opening of the windows than that of the buildings on the windward side,1~4 floors are 20.6% higher than the case of unopened windows. The change of indoor pollutant concentration on each floor is roughly consistent with the outdoor street canyon pollutant distribution. The indoor pollutant concentration of leeward buildings is much higher than that of windward buildings. Concentrations of indoor pollutants in leeward buildings decrease with the increase of floors, the pollutants on floors 1~4 account for 43.7% of the total pollution. The indoor pollutant concentration of buildings on the windward side first decreases along the building height, but does not show a monotonous trend of decreasing floor by floor. The pollutant concentration value is the smallest near the middle floor of building, then increases under the combined action of window disturbance and street canyon circulation vortex. The whole solution of street canyon-window building overcomes the inconsistency between the inflow level setting of simulated street buildings and the actual working conditions, better solves the problems of complex vortex boundary setting and different window opening positions from floor to floor.

Natural ventilation is a highly respected and effective way to improve indoor air quality, and single-sided natural ventilation is easily formed in residential buildings. The site experiments were carried out, and the unsteady characteristics of the airflow were analyzed based on 3D wind speed series. With the experimental verification, large-eddy simulation was successfully applied to calculate the indoor–outdoor flow field of urban building groups. When the entrance boundary was constant, the flow field of the window varied all the time, and outflow was irregular. The natural ventilation efficiency was 42% with the incoming flow almost parallel to the window. The discrete wind speed inlet boundary is more suitable for the natural ventilation simulation of buildings in a real environment than the average wind speed boundary and the average wind speed superposition ±10% disturbance. [ABSTRACT FROM AUTHOR]