Computational fluid dynamics models are resource-intensive, particularly when complex chemical schemes are implemented, and this computational expense limits their use in sensitivity analyses. We propose a flexible multi-box model that permits spatial disaggregation of sources and depositions to simulate the transportation and distribution of chemical species in street canyons with any aspect ratios for which a large eddy simulation (LES) of the flow exists. The spatial patterns of reactive species in the multi-box simulations are in good agreement with those from the LES, especially for the deep canyon from which air escapes more slowly. The overestimation of the LES simulation worsens somewhat due to segregations when the chemistry of volatile organic compounds (VOCs) is included but the overall pattern is captured in a modelling framework. By reducing computational costs by several orders of magnitude, the multi-box model allows more sensitivity testing than the LES, and is an effective approach to investigate spatial pattern of fast non-linear chemistry or microphysics at the street scale.

计算流体动力学模型是资源密集型的，尤其是在实施复杂的化学方案时，这种计算费用限制了它们在敏感性分析中的使用。我们提出了一个灵活的多盒模型，它允许源和沉积的空间分解来模拟街道峡谷中化学物质的运输和分布，其中任何纵横比存在流动的大涡模拟 (LES)。多盒模拟中反应性物质的空间模式与来自 LES 的那些非常一致，特别是对于空气逸出较慢的深峡谷。当包含挥发性有机化合物 (VOC) 的化学成分但在建模框架中捕获整体模式时，LES 模拟的高估会由于分离而有所恶化。