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 Kc 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.

中文翻译：

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建筑物表面温度升高对高层建筑周围气流和交叉污染的影响。

本文通过数值研究高层建筑周围的流场特性以及当建筑物表面被太阳辐射加热时的交叉污染。首先，使用归一化浓度Kc来评估在不同源位置下表面温度没有升高的情况下的色散特性。在等温条件下，预测结果揭示的近壁污染物扩散特征与我们以前的风洞实验相似。然后，分别基于近壁浓度分布和尾流涡旋核心位置，评估壁表面温度升高对交叉污染和流场的影响。当建筑物表面温度升高时，与等温条件下相比，涡流芯的位置明显改变。提出了下风向壁面温度升高到15 K以下时旋涡芯位置的修正公式。迎风壁表面温度的升高带来了更严重的污染物积累。当污染物从背风壁表面的底部和中间释放时，近壁浓度随温度的升高而增加，而顶部释放的情况则呈现相反的趋势。对于通常公认的理查森数Ri（Ri <0.1; 0.1 <Ri <10; Ri> 10）的三个区间范围，这些结果表明，当Ri小于0.1时，壁面温度升高对近壁流动的影响小规模模型的交叉污染不容忽视。迎风壁表面温度的升高带来了更严重的污染物积累。当污染物从背风壁表面的底部和中间释放时，近壁浓度随温度的升高而增加，而顶部释放的情况则呈现相反的趋势。对于通常公认的理查森数Ri（Ri <0.1; 0.1 <Ri <10; Ri> 10）的三个区间范围，这些结果表明，当Ri小于0.1时，壁面温度升高对近壁流动的影响小规模模型的交叉污染不容忽视。迎风壁表面温度的升高带来了更严重的污染物积累。当污染物从背风壁表面的底部和中间释放时，近壁浓度随温度的升高而增加，而顶部释放的情况则呈现相反的趋势。对于通常公认的理查森数Ri（Ri <0.1; 0.1 <Ri <10; Ri> 10）的三个区间范围，这些结果表明，当Ri小于0.1时，壁面温度升高对近壁流动的影响小规模模型的交叉污染不容忽视。而顶级发布方案则呈现出相反的趋势。对于通常公认的理查森数Ri（Ri <0.1; 0.1 <Ri <10; Ri> 10）的三个区间范围，这些结果表明，当Ri小于0.1时，壁面温度升高对近壁流动的影响小规模模型的交叉污染不容忽视。而顶级发布方案则呈现出相反的趋势。对于通常公认的理查森数Ri（Ri <0.1; 0.1 <Ri <10; Ri> 10）的三个区间范围，这些结果表明，当Ri小于0.1时，壁面温度升高对近壁流动的影响小规模模型的交叉污染不容忽视。