关于污染物跨户传播的先前研究大多基于孤立建筑，而建筑所处的城市形态会影

Most previous studies on the cross-household transmission of pollutants are based on isolated buildings, and the urban form of the building will affect the flow field around the building and change the route of the cross-household transmission of pollutants. <br><br>In this paper, computational fluid dynamics (CFD) is used to carry out a numerical simulation study on the cross-household transmission of pollutants from a single-sided natural ventilation building in a two-dimensional ideal street canyon. <br><br>First of all, the mathematical model used in the simulation was verified by using previous experimental data, and then the air flow and pollutant diffusion in the two-dimensional ideal street canyon and its buildings on both sides were simulated indoor and outdoor, and the room on different floors was compared and analyzed. Fresh air volume and the re-entry ratio of pollutants in other rooms when the pollution source is located in a room on a different floor. The research results show that the air flow in the street valley is mainly dominated by a clockwise main vortex centered at the center of the street valley; except for the rooms on the 7th floor on the leeward side, the ventilation capacity of the rooms on the windward side of the same floor is generally higher than that of the rooms on the leeward side; The ventilation capacity of the middle-level rooms is lower than that of the upper and lower-level rooms. Pollutants mainly diffuse between rooms on the same facade, and the diffusion capacity between rooms on different facades is weak. Under the action of the vortex in the street valley, the pollutants released from the rooms on the windward side will diffuse from top to bottom, while the pollutants released from the rooms on the leeward side will diffuse from bottom to top. When the pollution source is located on the windward side, the pollutant spreads more widely; the rooms adjacent to the pollution source along the cross-household transmission path are more affected by the cross-household transmission; when the pollution source is located in the room on the 6th floor on the leeward side, the room on the 7th floor The input ratio reaches the maximum value of about 15%. <br>[Keywords] two-dimensional ideal street valley; one-sided natural ventilation; cross-household transmission of pollutants; numerical simulation

Previous studies on the inter-house transmission of pollutants have been mostly based on isolated buildings, where the urban form of the building sits on the flow fields around the building and thus changes the route of cross-house transmission of pollutants.<br><br>In this paper, computational fluid mechanics (CFD) is used to carry out numerical simulation of the cross-house propagation of one-sided natural ventilation building pollutants in two-dimensional ideal street valley.<br><br>Firstly, the mathematical model used in the simulation was verified by the previous experimental data, and then the indoor-outdoor coupling simulation of the air flow and the diffusion of pollutants in the two-dimensional ideal street valley and its two-sided building rooms were compared and analyzed, and the new air volume of the rooms on different floors and the re-entry ratio of pollutants in other rooms when the pollution source was located in the room on different floors. The results show that the air flow in the street valley is mainly dominated by a clockwise main vortex in the center of the street valley, except for the 7th floor room on the backwind surface, the ventilation capacity of the airward room on the same floor is generally higher than that of the windward room, and the ventilation capacity of the windy mid-room is lower than that of the upper and lower-level rooms. Contaminants mainly spread between rooms on the same facade, and the diffusion capacity between rooms on different facades is weak. Under the street valley vortex, pollutants released in windward rooms will spread from top to bottom, while pollutants released from the backwind room will spread from the bottom up. The pollution source is located in the windward surface when the spread of the pollutant spread sawider, along the cross-house transmission path adjacent to the pollution source of the room is greatly affected by cross-house transmission, when the source of pollution is located in the 6th floor room of the leeward surface, the re-entry ratio of the room on the 7th floor of the leeward surface reaches a maximum of about 15%.<br>Two-dimensional ideal street valley; one-sided natural ventilation; cross-house propagation of pollutants; numerical simulation.

Most of the previous studies on the inter household transmission of pollutants are based on isolated buildings, and the urban form of the buildings will affect the flow field around the buildings, and then change the route of the inter household transmission of pollutants.<br>In this paper, computational fluid dynamics (CFD) is used to simulate the indoor contaminant transport in a two-dimensional ideal street canyon with natural ventilation.<br>Firstly, the mathematical model used in the simulation is verified by the previous experimental data. Then, the indoor and outdoor coupling simulation of air flow and pollutant diffusion in the two-dimensional ideal Street Valley and the building rooms on both sides are carried out. The fresh air volume of rooms on different floors and the re-entry ratio of pollutants in other rooms when the pollution source is located in rooms on different floors are compared and analyzed. The results show that the air flow in the street canyon is mainly dominated by a clockwise main vortex with its center located in the center of the street valley; the ventilation capacity of the windward side rooms on the same floor is generally higher than that of the leeward side rooms, and the ventilation capacity of the middle-level rooms on the windward side is lower than that of the high-rise and low-rise rooms. The pollutant mainly diffuses between rooms on the same facade, and the diffusion ability between rooms with different facades is weak. Under the action of street canyon vortex, the pollutants released from the windward room will diffuse from top to bottom, while the pollutants released from the leeward side room will diffuse from the bottom to the top. When the pollution source is located on the windward side, the diffusion range of pollutants is wider; the room adjacent to the pollution source along the cross household transmission path is greatly affected by the cross household transmission; when the pollution source is located in the room on the sixth floor of the leeward side, the reentry ratio of the seventh floor room on the leeward side reaches the maximum value of about 15%.<br>[Key words] two dimensional ideal Street valley; one side natural ventilation; inter household pollutant transmission; numerical simulation<br>