[Construction of urban ventilation corridor based on computational fluid dynamics and circuit theory: A case study of...

Ventilation corridors play an important role in alleviating the urban heat island effect and promoting air circulation, which is of great significance for improving the urban wind and heat environment and enhancing the quality of life of residents. However, the available methods for constructing ventilation corridors have limitations in terms of the balance among computational cost, spatial accuracy and research scope, as well as the identification of multiple air flow paths. Moreover, those methods mostly simplify air flow by using macroscopic wind direction and external fixed entrances and exits, overlooking the potential of internal urban wind sources and the spatial heterogeneity of the wind environment. In response to the above issues, we proposed a new technical framework for the construction of ventilation corridors and took Nanjing central urban area as an example to elaborate its implementation process. Firstly, we used the computational fluid dynamics (CFD) simulation to obtain the near-ground wind field, and carried out the multi-factor comprehensive evaluation of urban ventilation corridor construction suitability. Then, we identified the urban ventilation corridor by combining circuit theory with the land surface thermal environment. Finally, we constructed an urban ventilation corridor system composed of wind sources, corridors, and restoration zones. To test the effectiveness of this framework and evaluate its advantages, we conducted a comparative analysis using the least cost path method based on the frontal area index (FAI-LCP method). The results based on the technical frame work of this study showed that there were 6 core wind sources, 19 secondary wind sources, 9 primary ventilation corridors and 10 secondary corridors in the urban ventilation corridor system of Nanjing central urban area. Based on the normalized current flow results obtained from circuit theory, 14 restoration zones of the ventilation corridor system were identified, mainly distributed in the downwind areas of the internal wind sources and the areas with a higher frontal area index in the secondary ventilation corridors. Compared with the FAI-LCP method, our technical framework could achieve the identification of internal wind sources, the characterization of corridor width and the discrimination of ventilation obstruction points, which would be conducive to enhancing the systematicness of ventilation corridor planning.