Dataset associated with manuscript titled "Wake Characteristics of Multiscale Buildings in a Turbulent Boundary Layer"

Abstract from the manuscript associated with this dataset:Urban forms characterised by multi-scale roughness can drastically modify the wind structure within cities affecting both pedestrian comfort and air quality at street level. For simplicity, most urban flow studies focus on cuboid buildings with a single length scale. We consider six forms to assess how additional length scales impact urban flow: two reference cuboid cases (standard and tall) that differ in aspect ratio (mean building height to width), plus two additional fractal iterations of each}. The six models have the same mean building width, height, and frontal area but their length scale characteristics differ. These are used in wind tunnel experiments within a deep turbulent boundary layer. The length scale differences are found to affect the drag force exerted by the buildings in a non-negligible way (up to 5% and 13% for standard and tall buildings, respectively). The added length scales also modify the wake lateral spread and intensity of the turbulence fluctuations, with the smaller length scales having the lower (higher) intensity of fluctuations in the near (far) wake. Additionally, the strength of the vortex shedding emanating from the buildings is reduced by introducing systematically smaller length scales. This work suggests that the omission of additional length scales can lead to inaccuracies in drag and wake recovery estimations. The reduction in the intensity of vortex shedding found with each fractal iteration could have engineering applications (e.g. reducing vibration).

本数据集关联学术论文的摘要如下：以多尺度粗糙度（multi-scale roughness）为特征的城市形态，可显著改变城市内部的风场结构，进而影响街道层面的行人舒适度与空气质量。为简化研究，多数城市气流相关研究均聚焦于单一长度尺度的长方体建筑（cuboid buildings）。本研究选取六种建筑形态，以探究额外长度尺度对城市气流的影响：其中两种为基准长方体建筑工况（标准型与高耸型），二者的高宽比（aspect ratio，即建筑平均高度与宽度之比）存在差异；此外针对每种基准工况额外开展两次分形迭代（fractal iterations）。六种模型的建筑平均宽度、高度及迎风面积（frontal area）均保持一致，但长度尺度特征存在差异。上述模型被应用于深厚湍流边界层（deep turbulent boundary layer）环境下的风洞实验。研究发现，长度尺度差异对建筑所受阻力（drag force）的影响不可忽视：标准型与高耸型建筑的阻力变化幅度分别可达5%与13%。额外引入的长度尺度还会改变尾流横向扩展（wake lateral spread）特性与湍流脉动（turbulence fluctuations）强度：较小的长度尺度会使近尾流区的脉动强度更低，远尾流区的脉动强度更高。此外，系统性引入更小的长度尺度会削弱建筑产生的漩涡脱落（vortex shedding）强度。本研究表明，忽略额外长度尺度会导致阻力与尾流恢复预测的精度出现偏差。本次分形迭代观测到的漩涡脱落强度减弱现象，可应用于相关工程场景（例如降低振动）。