Lim H D, Hertwig Denise, Grylls Tom, Gough Hannah, Reeuwijk Maarten van, Grimmond Sue, Vanderwel Christina
Aeronautics and Astronautics Department, University of Southampton, Southampton, UK.
Department of Meteorology, University of Reading, Reading, UK.
Exp Fluids. 2022;63(6):92. doi: 10.1007/s00348-022-03439-0. Epub 2022 May 23.
Pollutant dispersion by a tall-building cluster within a low-rise neighbourhood of Beijing is investigated using both full-scale Large-Eddy Simulation and water flume experiments at 1:2400 model-to-full scale with Particle Image Velocimetry and Planar Laser-Induced Fluorescence. The Large-Eddy Simulation and flume results of this realistic test case agree remarkably well despite differences in the inflow conditions and scale. Tall buildings have strong influence on the local flow and the development of the rooftop shear layer which dominates vertical momentum and scalar fluxes. Additional measurements using tall-buildings-only models at both 1:2400 and 1:4800 scales indicates the rooftop shear layer is insensitive to the scale. The relatively thicker incoming boundary layer affects the Reynolds stresses, the relative size of the pollutant source affects the concentration statistics and the relative laser-sheet thickness affects the spatially averaged results of the measured flow field. Low-rise buildings around the tall building cluster cause minor but non-negligible offsets in the peak magnitude and vertical location, and have a similar influence on the velocity and concentration statistics as the scale choice. These observations are generally applicable to pollutant dispersion of realistic tall building clusters in cities. The consistency between simulations and water tunnel experiments indicates the suitability of both methodologies.
利用全尺寸大涡模拟和1:2400模型比尺的水槽实验，结合粒子图像测速技术和平面激光诱导荧光技术，研究了北京低层社区内高层建筑群的污染物扩散情况。尽管流入条件和尺度存在差异，但该实际测试案例的大涡模拟和水槽实验结果吻合得非常好。高层建筑对局部流动以及主导垂直动量和标量通量的屋顶剪切层的发展有很大影响。使用1:2400和1:4800尺度的仅高层建筑模型进行的额外测量表明，屋顶剪切层对尺度不敏感。相对较厚的入流边界层影响雷诺应力，污染物源的相对大小影响浓度统计，相对激光片厚度影响测量流场的空间平均结果。高层建筑群周围的低层建筑会在峰值大小和垂直位置上产生微小但不可忽略的偏移，并且对速度和浓度统计的影响与尺度选择类似。这些观察结果通常适用于城市中实际高层建筑群的污染物扩散。模拟和水洞实验之间的一致性表明了这两种方法的适用性。
