The prediction of dispersion of gases emitted from rooftop stacks in a built environment is important for preventing or minimizing their harmful effects on human health. In this study, the wind flow and dispersion of exhaust gas emitted from rooftop stacks on buildings in an urban environment under different atmospheric thermal stabilities were investigated using numerical simulations. The wind flow field and dispersion contaminants were simulated using a computational fluid dynamics model with the k-ε turbulent schemes being resolved by the Reynolds-averaged Navier–Stokes approach. An isolated building was modeled under conditions of varying thermal stratification of the boundary layers (neutral, unstable, and stable conditions). The diffusion flow field within the building wake zone was investigated for various stack sites (center, right side, and left side). Experiments were conducted in a wind tunnel to validate the numerical simulation results, by using the data qualitatively and quantitatively. The numerical simulation results were consistent with the experimental observations. The results indicated that the pollutant concentration of the plume spread was high near the stack and decreased with increasing distance from the stack. Under stable conditions, the flow motion and separation increased in the wake zone, and the pollutant concentration of the lateral spread at the average human height decreased. Under unstable conditions, the flow of the vortex circulation was fast and strong, and the pollutant concentration of the vertical spread was high.

从屋顶烟囱排放的气体在建筑环境中的扩散预测对于防止或最大程度地减少其对人体健康的有害影响非常重要。在这项研究中，使用数值模拟研究了在不同大气热稳定性下城市环境中建筑物屋顶叠层排放的风流和废气扩散。使用计算流体动力学模型模拟了风流场和弥散污染物，其中k-ε湍流方案通过雷诺平均Navier-Stokes方法求解。在边界层热分层变化的条件下（中性，不稳定和稳定条件）对隔离的建筑物进行建模。研究了建筑物尾流区内不同堆垛位置（中心，右侧，和左侧）。通过定性和定量地使用数据，在风洞中进行了实验以验证数值模拟结果。数值模拟结果与实验结果一致。结果表明，烟羽的污染物浓度在烟囱附近较高，并随着距烟囱距离的增加而降低。在稳定的条件下，尾流区的水流运动和分离增加，人的平均身高侧向扩散的污染物浓度降低。在不稳定条件下，涡旋环流快速而强劲，垂直扩散的污染物浓度较高。通过定性和定量地使用数据。数值模拟结果与实验结果一致。结果表明，烟羽的污染物浓度在烟囱附近较高，并随着距烟囱距离的增加而降低。在稳定条件下，尾流区的水流运动和分离增加，人的平均身高横向扩散的污染物浓度降低。在不稳定条件下，涡旋环流快速而强劲，垂直扩散的污染物浓度较高。通过定性和定量地使用数据。数值模拟结果与实验结果一致。结果表明，烟羽的污染物浓度在烟囱附近较高，并随着距烟囱距离的增加而降低。在稳定的条件下，尾流区的水流运动和分离增加，人的平均身高横向扩散的污染物浓度降低。在不稳定条件下，涡旋环流快速而强劲，垂直扩散的污染物浓度较高。结果表明，烟羽的污染物浓度在烟囱附近较高，并随着距烟囱距离的增加而降低。在稳定的条件下，尾流区的水流运动和分离增加，人的平均身高侧向扩散的污染物浓度降低。在不稳定条件下，涡旋环流快速而强劲，垂直扩散的污染物浓度较高。结果表明，烟羽的污染物浓度在烟囱附近较高，并随着距烟囱距离的增加而降低。在稳定的条件下，尾流区的水流运动和分离增加，人的平均身高侧向扩散的污染物浓度降低。在不稳定条件下，涡旋环流快速而强劲，垂直扩散的污染物浓度较高。