Relevant drag measurements in wind tunnels contributed to the drag parametrization. This reduced-scale numerical work further examines drag distribution and the relation between drag force and outdoor ventilation efficiency. Neighbourhood-like block arrays with planar area densities (λp) from 0.0625 to 0.25 and five distinct form types are investigated, extending a prior drag experiment solely on cube regular arrays. The approaching flow reshaped by these arrays exhibits flow adjustment and drag evolution. Drag distribution analysis demonstrates varied shelter effects and different shapes of sectional drag profiles. Arrays featuring larger λp and staggered layout generally exhibit higher normalized bulk drag force (Fbulk∗), but lower normalized frontal area-averaged drag (FAf,ave∗). Further, Fbulk∗ and FAf,ave∗ demonstrate strong negative correlations with normalized spatially averaged velocity, showing the potential to reflect the ventilation efficiency within neighbourhoods. Drag area density and drag-to-frontal area ratio are assessed as alternatives to interpret the drag, and it reveals half of the physical frontal area for medium arrays can serve as approximately estimated drag area. It is noted that the qualitative evaluation provides insights into the drag distribution and drag interpretation, while the quantitative correlation is limited to the examined morphological scenarios.

中文翻译：

---

从阻力和通风效率的角度对中低密度邻里区周围气流进行降尺度数值研究


风洞中的相关阻力测量有助于阻力参数化。这项缩小比例的数值工作进一步检查了阻力分布以及阻力与室外通风效率之间的关系。研究了平面面积密度 （λp） 从 0.0625 到 0.25 的邻里状块阵列和五种不同的形式类型，扩展了先前仅在立方体正则阵列上的阻力实验。由这些阵列重塑的接近流表现出流动调整和阻力演变。阻力分布分析展示了不同的庇护所效应和不同形状的截面阻力剖面。具有较大 λp 和交错布局的阵列通常表现出较高的归一化体阻力 （Fbulk∗），但较低的归一化正面面积平均阻力 （FAf，ave∗）。此外，Fbulk∗ 和 FAf，ave∗ 与归一化空间平均速度呈强负相关，显示出反映社区内通风效率的潜力。阻力面积密度和阻力与正面面积之比被评估为解释阻力的替代方案，它揭示了中型阵列的物理正面面积的一半可以作为近似估计的阻力面积。值得注意的是，定性评估提供了对阻力分布和阻力解释的见解，而定量相关性仅限于检查的形态学情景。