城市建筑物对边界层结构影响的数值试验研究

The Numerical Experiments of the Effect of Urban Buildings on Boundary Layer Structure

在区域边界层模式的数值模拟中引入建筑物的影响,与实际观测的对比表明,模拟结果能较好地体现建筑物对城市风场的影响,提高了模拟性能。本研究根据城市形态特征,设计不同建筑物高度和密度的敏感性试验,结果表明:建筑物一般会使城市地区风速减小,风速最大可减小1.6 m/s,易引起低层气流的辐合。湍流动能中的机械产生作用增加,湍流交换加强,大气层结的不稳定性增大,混合层高度增加。地表和大气之间动量交换被削弱;日间热量交换减弱,夜间热量交换增强。这些变化表明,建筑物对城市气流及边界层结构的影响十分明显,尤其在风速较大的时候。

Building＇s effect is developed in Regional Boundary Layer Model. The simulated results illustrate that it can simulated the effect of buildings on urban air flow field. According to the urban morphology, we design the different building heights and densities, The simulated results show that the buildings can weaken the wind speed in urban area and lead to convergence in lower layer atmosphere. The weaken can reach a peak of 1.6 m/s. The dynamic production of turbulence is strengthened and the turbulence transportation is greater. The presence of building leads to a more instable stratification with a mixing layer. The top of boundary layer can improved . It leads to a weaker energy exchange between atmosphere and the earth. In daytime the heat exchange between atmosphere and the earth is weakened while strengthened at night. All of the simulations illustrate that the buildings play an important role in urban air flow field and boundary layer structure, particularly when wind speed is great.