The Study Of Urban Construction Area Pollutant Diffusion And Its Effects Of Indoor Natural Ventilation

With the rapid development of modern city, the environmental problems in large and medium-sized cities has received extensive attention in many fields, fog and haze weather is increasingly serious in the cities. The environmental quality of construction area reduced obviously. The buildings in cities and its ambient area is the main place for people to live and live in. So the study of pollutants inside the village construction conditions and corresponding improvement measures have important practical significance. Natural ventilation has a great potential of saving energy, which has significant environmental advantages and it is widely applied in the field of architecture. Based on the coupling method of the indoor and outdoor fluid flow and pollutant diffusion, outdoor air and pollutants flow into indoor. However, in the case of building area pollutant diffusion, outdoor air may be also polluted, indoor pollutants is likely to be introduced by natural ventilation, which affects the indoor air quality.Firstly, a building in Jinan district is taked as the model for the numerical study in this article. This paper describes the regularities of the flow field inside building community and the law of pollutant diffusion and its diffusion pattern. Then pollutant concentration field and flow field of the construction area are simulated under different conditions, such as different wind direction, wind speed and different background concentration by means of CFD simulation method. At the same time, based on the similarity theory and dimensional analysis method in the fluid mechanics design, building physical model is manufactured. The flow field of the model is be measured by means of PIV in the built environment wind tunnel test. The test measurement data were compared with the numerical simulation data. Finally the flow field around the building and the concentration field of pollutant dispersion are analysed systematically. Theoretical analysis is carried out on the effect of flow field on the diffusion of pollutant concentration field. Based on the indoor and outdoor environment flow field and concentration field coupling, indoor natural ventilation of the building area are simulated and analysed.The following results can be found from the convection diffusion distribution of building community numerical simulation. The wind direction has a great influence on the convection field, which can cause significant difference of the flow field and pollutant concentration field in the building area. The wind speed has also a great influence on the convection field. The higher the wind speed, the better the diffusion and dilution of pollutants. The higher the air quality level, the greater the background concentration, the greater the concentration of pollutants, the more complex the change of the law of diffusion.On the basis of numerical simulation, the flow field around the building area model is measured and analyzed by the wind tunnel test technique. The model results are translated into the prototype, the results are found that the two are basically consistent, which verified the correctness of the mathematical model and the accuracy of the numerical calculation.Based on flow field and concentration field coupling between the indoor and outdoor, indoor natural ventilation is simulated by CFD. In any case, the indoor contaminant basically reach the stable state after a certain time. Compared with the outdoor background concentration, a certain degree of attenuation of the concentration of indoor pollutants appears.In conclusion, the research results of this paper can provide scientific basis for the planning layout, building height and floor space control, room layout design and room comfort design.