This paper proposes a computational fluid dynamics (CFD) model, along with dimensionless quantitative assessment standard—air pollution residual time (APRT) for the evaluation of local haze-fog (HF) dispersion in a built environment. A low APRT value ensures good ventilation. A building group model that comprises high-rise business building, mid-rise office buildings, low-mid-rise residential buildings (at the center of the building group), a mid-rise recreational center, and a local road (open terrain), was scaled down (1:100) to simulate the HF dispersion process. The orientation of the building group was numerically modified to generate a wind incidence normal to the high-rise building, mid-rise buildings, recreational center, and road. The results showed that the orientation of the building group largely determines the APRT. The most favorable orientation can reduce APRT by more than 50%. Our results strongly suggested that in order to reduce the consequential negative effect of air pollution, future urban designs should undergo a comprehensive ventilation assessment to ensure a low APRT value.

本文提出了一种计算流体动力学（CFD）模型，以及无量纲的定量评估标准-空气污染残留时间（APRT），用于评估建筑环境中的局部雾霾（HF）扩散。低APRT值可确保良好的通风。一个建筑群模型，包括高层商务楼，中层办公楼，中低层住宅楼（在建筑群的中心），中层娱乐中心和本地道路（开阔地带） ，按比例缩小（1：100），以模拟HF分散过程。对建筑物组的方向进行了数字修改，以生成垂直于高层建筑物，中层建筑物，娱乐中心和道路的风入射。结果表明，建筑群的定位很大程度上决定了APRT。最有利的定位可以使APRT降低50％以上。我们的结果强烈建议，为了减少空气污染的负面影响，未来的城市设计应进行全面的通风评估，以确保较低的APRT值。