Cross-ventilation flow in buildings is dominantly impacted by the characteristics of their surrounding built environment, specifically in highly-dense urban areas. Cross-ventilation in highly-dense urban configurations is studied using validated computational fluid dynamics models using the large eddy simulation approach. Mean flow properties, turbulent statistics, wind pressure, and crossing airflow rate are compared against different planar area ratios of $0\le {\lambda }_p\le 0.6$ and approaching wind angles of $0°\le \alpha \le 90°$ for a generic building model surrounded by nine identical building models. The transient airflow rate is analyzed considering different airflow definitions based on the time-averaged and fluctuating velocity decomposition. It is found that the difference between the time-averaged and instantaneous airflow rate is not negligible in a highly-dense urban configuration where the velocity is generally weak, but the flow direction is highly fluctuating. Furthermore, it is shown that time-averaged airflow rate calculations are not suitable for accurate prediction of cross-ventilation in sheltered buildings in medium and highly-dense urban configurations; this is because of the averaging procedure cancels out the velocity fluctuation and periodic flows through the openings. Moreover, it is proposed that the accumulative instantaneous ventilation rate can be more suitable for airflow rate calculations as it includes the instantaneous airflow exchanges.

建筑物中的交叉通风流量主要受周围建筑环境特征的影响，特别是在高密度的城市地区。使用大涡模拟方法，使用经过验证的计算流体动力学模型研究高密度城市配置中的交叉通风。将平均流动特性，湍流统计数据，风压和交叉气流速率与不同的平面面积比进行比较$0\le {\lambda }_p\le 0.6$ 并接近风向 $0°\le \alpha \le 90°$包含九个相同建筑模型的通用建筑模型。基于时间平均和波动速度分解，考虑不同的气流定义来分析瞬态气流速率。结果发现，在速度通常较弱但流动方向高度波动的高度密集的城市配置中，时间平均流速与瞬时空气流速之间的差异不可忽略。此外，研究表明，时间平均气流速率计算不适合准确预测中等密度和高密度城市环境中带遮盖建筑物的交叉通风；这是因为平均过程抵消了速度波动和周期性的流过开口的现象。此外，