Natural ventilation, a useful mechanism to moderate the indoor temperature and to disperse pollutants, is a complex engineering problem to analyze due to a large number of influential factors such as wind direction, size, and location of openings, etc. The present paper investigates the effect of different shapes of openings, with a constant wall porosity, namely, horizontally long, squared and vertically long, on cross-ventilation in a generic isolated building. Flow and passive pollutant concentration fields are the performance indicators. The large eddy simulation (LES) approach together with the wall-adapting local eddy-viscosity (WALE) sub-grid scale (SGS) model is employed for the simulations. Validation results, based on available wind-tunnel measurements, of time-averaged velocity and pollutant concentration for the reference case are reported. Results display that the performance of cross-ventilation in reducing the pollutant concentration enhances as the height to width ratio of the openings increases and the building with horizontally long openings is the most contaminated case. The ventilation performance in the case of vertically long openings is shown to be the most effective one. Furthermore, present findings show that the participation of the turbulent diffusion flux in the passive pollutant transportation becomes smaller as the flow makes progress toward the downstream.

自然通风是调节室内温度和分散污染物的有用机制，由于风向，大小和开口位置等诸多影响因素，因此是一个复杂的工程问题，需要分析。在普通隔离式建筑物中，具有恒定孔隙率（水平长，正方形和垂直长）的不同形状的开口对交叉通风的影响。流量和被动污染物浓度场是性能指标。仿真中采用了大涡模拟（LES）方法，以及适应壁的局部涡粘性（WALE）子网格比例（SGS）模型。验证结果基于可用的风洞测量，报告了参考案例的平均时速和污染物浓度。结果表明，交叉通风在降低污染物浓度方面的性能随着开口的高宽比的增加而增强，并且开口水平较长的建筑物是受污染最严重的情况。垂直较长的开口情况下的通风性能被证明是最有效的。此外，目前的发现表明，湍流扩散通量在被动污染物输送中的参与随着流向下游的发展而变小。结果表明，交叉通风在降低污染物浓度方面的性能随着开口的高宽比的增加而增强，并且开口水平较长的建筑物是受污染最严重的情况。垂直较长的开口情况下的通风性能被证明是最有效的。此外，目前的发现表明，湍流扩散通量在被动污染物输送中的参与随着流向下游的发展而变小。结果表明，交叉通风在降低污染物浓度方面的性能随着开口的高宽比的增加而增强，并且开口水平较长的建筑物是受污染最严重的情况。垂直较长的开口情况下的通风性能被证明是最有效的。此外，目前的发现表明，湍流扩散通量在被动污染物输送中的参与随着流向下游的发展而变小。