School of Civil Engineering, Hefei University of Technology, Hefei, 230009, Anhui, China.
First Design and Research Institute MI China Co. Ltd., Hefei, 230601, Anhui, China.
Environ Sci Pollut Res Int. 2020 Apr;27(11):11855-11869. doi: 10.1007/s11356-020-07671-1. Epub 2020 Jan 24.
This paper numerically studies the characteristics of flow field around a high-rise building and the cross-contamination when the building surface is heated by the solar radiation. Firstly, the normalized concentration K is used to evaluate the dispersion characteristics under different source locations without surface temperature rise. Under iso-thermal condition, the near-wall pollutant dispersion features revealed by the predicted results are similar to our previous wind tunnel experiment. Then, the effect of wall surface temperature rise on the cross-contamination and the flow fields is evaluated based on the near-wall concentration distributions and the wake zone vortex core positions, respectively. When the building surface temperature rises, the location of vortex core obviously changes comparing with that under iso-thermal condition. The correction formula for the vortex core location with the leeward wall surface temperature rise below 15 K is developed. The windward wall surface temperature rise brings more serious pollutant accumulation. The near-wall concentrations increase with the rise of temperature when the pollutant is released from the bottom and middle of leeward wall surface, while the top-release scenario exhibited a contrary tendency. For the three interval ranges of generally recognized Richardson number Ri (Ri < 0.1; 0.1 < Ri < 10; Ri > 10), these results indicate that when Ri is less than 0.1, the effect of wall surface temperature rise on near-wall flow and cross-contamination of small-scale model cannot be ignored.
本文通过数值模拟的方法研究了太阳辐射加热下高层建筑表面附近流场特性和交叉污染问题。首先，在无表面温升的情况下，通过归一化浓度 K 来评估不同源位置的扩散特性。在等温条件下，预测结果揭示的近壁面污染物扩散特征与我们之前的风洞实验结果相似。然后，根据近壁面浓度分布和尾流区涡核位置，分别评估了壁面温升对交叉污染和流场的影响。当建筑表面温度升高时，涡核位置与等温条件下相比明显发生变化。提出了一种适用于背风壁面温升低于 15 K 的涡核位置修正公式。迎风壁面温升会导致更严重的污染物积聚。当污染物从背风壁面底部和中部释放时，近壁面浓度随温度升高而增加，而顶部释放时则呈现相反的趋势。对于公认的理查森数 Ri 的三个间隔范围（Ri<0.1；0.1<Ri<10；Ri>10），这些结果表明当 Ri 小于 0.1 时，壁面温度升高对小尺度模型近壁面流动和交叉污染的影响不容忽视。
