Abstract This study reports the results of large eddy simulations with the standard Smagorinsky model of the velocity fields within a cross-ventilation model sheltered by block arrays. A very fine resolution of 1/100 of the building height was adopted. The objectives are to understand the sheltering effect of the surrounding building array and quantify the ventilation rate in the cross-ventilation model. Two types of block arrays and opening positions were simulated. Comparisons of the numerical and experimental results justify that the present simulations reproduced the characteristics of the mean as well as turbulent flows introduced in the ventilation model. In addition, the simultaneous observations of the outdoor and indoor velocities enabled us to conclude that the change in the outdoor flow patterns caused a dramatic change in the indoor velocity distributions, although the opening position was identical in all such cases. Using these detailed flow fields, we compared three types of ventilation rates: the net, gross, and instantaneous ventilation rates. Moreover, we estimated the instantaneous ventilation rate using a random variable following the Gaussian distribution. The ventilation due to the turbulent inflow was crucial in the model with its opening on the lateral side of the block, whereas the mean flow primarily determined the ventilation rate for the block with its opening on the streamwise walls. In both cases, the estimation model could predict the instantaneous ventilation rate well with a maximum overestimation of only 3%. This means that the model was justified for all the present array and opening conditions.

中文翻译：

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类似城市街区阵列遮挡的普通街区交叉通风流数值模拟

摘要 本研究报告了使用块阵列遮蔽的交叉通风模型内速度场的标准 Smagorinsky 模型进行大涡模拟的结果。采用了建筑物高度的 1/100 的非常精细的分辨率。目标是了解周围建筑物阵列的遮蔽效果并量化交叉通风模型中的通风率。模拟了两种类型的块阵列和开口位置。数值和实验结果的比较证明，目前的模拟再现了通风模型中引入的平均和湍流的特征。此外，室外和室内速度的同时观察使我们能够得出结论，室外流动模式的变化导致室内速度分布的剧烈变化，尽管在所有这些情况下的开口位置都是相同的。使用这些详细的流场，我们比较了三种类型的通风率：净通风率、总通风率和瞬时通风率。此外，我们使用遵循高斯分布的随机变量来估计瞬时通气率。由于湍流流入导致的通风在模型中至关重要，其开口位于块的侧面，而平均流量主要决定了其开口在流向壁上的块的通风率。在这两种情况下，估计模型可以很好地预测瞬时通风率，最大高估仅为 3%。这意味着该模型对于所有当前阵列和打开条件都是合理的。