Key Laboratory of Hydraulic Machinery Transients, Wuhan University, Ministry of Education, Wuhan, Hubei Province, China; School of Power and Mechanical Engineering, Wuhan University, Wuhan, Hubei Province, China; Institute of Industrial Science, The University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo 153-8505, Japan.
Key Laboratory of Hydraulic Machinery Transients, Wuhan University, Ministry of Education, Wuhan, Hubei Province, China; School of Power and Mechanical Engineering, Wuhan University, Wuhan, Hubei Province, China.
Sci Total Environ. 2020 Jun 20;722:137924. doi: 10.1016/j.scitotenv.2020.137924. Epub 2020 Mar 13.
Periodic vortex shedding around a building could play an important role in wind-driven single-sided ventilation especially when two free openings are mounted on the leeward wall, in which case "pumping" flow dominates the natural ventilation. In this paper, we investigated the characteristics of vortex shedding and "pumping" flow affected by the arrangements of upstream buildings and opening area ratio of ports on the downstream target building. Computational fluid dynamics (CFD) simulations have been used to predict the instantaneous and mean flow fields. Numerical results indicate that the strength of "pumping" flow could be intensively weakened by two upstream buildings. Vortex shedding from the inner shear layers dominates the vortex shedding from the target building and constrains that from both upstream buildings except at W/B = 0.5, in which case the gap flow is weak and the St is close to that of a single building. The increase of upstream building length leads to decrease of the vortex shedding frequency at the wake of all buildings and ventilation rate of the downstream building. An increase of opening area ratio on the rear wall of the downstream building will raise the Strouhal number but have no positive correlation with ventilation rate. "Pumping" flow oscillating frequency does not have clear correlation with the ventilation rate. Our study on the wake vortex shedding flow across building clusters could benefit the future green design of urban buildings.
周期性涡旋脱落会在建筑物周围发生，这对风驱动的单面通风尤其重要，尤其是当两个自由开口安装在背风墙上时，此时“抽吸”流会主导自然通风。在本文中，我们研究了上游建筑物布置和下游目标建筑物端口的开口面积比对涡旋脱落和“抽吸”流特征的影响。使用计算流体动力学（CFD）模拟来预测瞬时和平均流场。数值结果表明，两个上游建筑物会强烈削弱“抽吸”流的强度。来自内部剪切层的涡旋脱落主导着来自目标建筑物的涡旋脱落，并限制了来自两个上游建筑物的涡旋脱落，除了在 W/B=0.5 处，此时间隙流较弱，St 接近单个建筑物的 St。上游建筑物长度的增加会导致所有建筑物尾流的涡旋脱落频率和下游建筑物的通风率降低。增加下游建筑物后壁上的开口面积比会提高斯特劳哈尔数，但与通风率没有正相关关系。“抽吸”流的振荡频率与通风率没有明显的相关性。我们对建筑物群尾流涡旋脱落的研究有助于未来城市建筑物的绿色设计。
