Abstract Although most people live in cities, the pollutant transport in so-called street canyons is still not well understood. The main reason is the complexity of the problem, where the roof shape, roof height and position of the pollutant source within a 3D urban array may play a significant role. This paper tries to improve the understanding and investigates the pollutant transport in six different types of street canyons using large-eddy simulations (LES). All street canyons were part of four different 3D urban arrays and differed in the roof shape and height. The results demonstrate that roof shape, roof-height non-uniformity, and the source position have a crucial impact on the advective and turbulent pollutant transport between the studied canyons and urban arrays. Both the flat roofs and roof-height variability enhance the lateral transport between the street canyons and intersections irrespective of the studied cases. This is crucial for the evaluation of the street canyon pollution if one changes the position of the source within the non-uniform urban array. Although the differences in the pollutant transport between the flat and pitched roofs mitigate in the cases of the variable roof heights, they are still appreciable.

中文翻译：

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屋顶形状、屋顶高度不均匀性和源位置对街道峡谷与3D城市阵列之间污染物传输的综合影响

摘要 尽管大多数人都生活在城市中，但人们对所谓的街道峡谷中的污染物运输还不是很了解。主要原因是问题的复杂性，其中屋顶形状、屋顶高度和污染源在 3D 城市阵列中的位置可能会发挥重要作用。本文试图通过大涡模拟 (LES) 提高对六种不同类型街道峡谷中污染物迁移的理解和研究。所有街道峡谷都是四个不同 3D 城市阵列的一部分，屋顶形状和高度各不相同。结果表明，屋顶形状、屋顶高度的不均匀性和源位置对研究的峡谷和城市阵列之间的平流和湍流污染物传输具有至关重要的影响。无论所研究的情况如何，平屋顶和屋顶高度可变性都增强了街道峡谷和十字路口之间的横向运输。如果在非均匀城市阵列中改变源的位置，这对于评估街道峡谷污染至关重要。尽管在屋顶高度可变的情况下，平屋顶和斜屋顶之间污染物传输的差异有所缓解，但它们仍然是可观的。