Aeration mode of main streets in high-density development

The aeration mode of urban areas in design practice is established for different geographic regions depending on the initial wind speed taking into account the human thermal state and the quality of atmospheric air. The purpose of the research is to assess the design, building and geometric parameters of the city streets influence on the airflow transformation and the atmospheric air pollution level. Based on the research results in full-scale conditions and on residential units' models, the features of the main streets aeration mode formation and the gas contamination level were revealed. It was found that the variations in wind speed and the distribution of pollutants in street canyons with a change in their width are connected with the formation of buildings flow regimes: along the envelope, turbulent-jet and isolated ones. The planning conditions that contribute to the formation of a stable vortex connected with the closed circulation of impurities in the street canyons were determined. Town-planning hygienic recommendations are given to regulate the streets aeration regime in order to ensure standards for the content of residential units' atmospheric pollution in the air, to protect urban residents from cold strong winds or to maintain the initial wind speeds in residential units.