Numerical Simulation And Analysis Of Pollutant Dispersion In The Resident District

Ambient air pollution has received more and more attentions in many scientific fields with increasing in urbanization and industrialization in China. Traffic emission is believed as the main air pollution source in the urban environment in current days, it is identified that the automobile exhaust discharges mainly between 0.3~2 meters, and long term exposed to this situation will do harm to people's health. And the resident district is the main place for people's living and leisure, to research the pollutant dispersion in the resident district is of great realistic significance.Based on the method of CFD (Computational Fluid Dynamics), the research takes a newly-built resident district in Harbin as the object of numerical simulation and monitoring. After establishing the physical and mathematical model of the resident district, the paper analyzes the airflow and dispersion of vehicle exhaust gas using 3D numerical simulation under four different kinds of states, which considers vehicle exhaust gas (nitrogen oxide) as the main source of pollution.The results show that the state of flow field around building group is different when under the same wind speed and different direction. And the flow process is more complex than the single building, besides all the characteristics such as the breakaway and the backflow, which produces in the single building, but also has mutual influence among the buildings. Around the building group produces partial turbulence, these rapids areas are controlling the pollutant dispersion. In the rapids and the low speed places around the building group, may induce the accumulation of pollutant. Pollutant concentrations will decrease as the distance from measuring point to source increase. Vertical distribution of pollutant concentrations is in accordance with the rules of source on the ground. Pollutant concentrations will spread broadly as the wind speed rise, therewith the local concentrations decrease.Comparing the simulation results with the sampling analysis, it indicates that the simulation value and the monitor value are quite consistent in the tendency, which proves the validity of the model. The error analysis further indicates the tally of monitoring and numerical simulation. The average deviation is only 0.013mg/m3, the average proportional error is only 0.406.Carrying on the numerical simulation through the CFD method to the simulati- on of the district, can provide us a more intuitionistic image and visible result. which can be served for the layout design and environmental assessment more conveniently and effectively. The simulation results made reference to the layout design and environmental evaluation of the resident district.