The impact of building surface temperature rise on airflow and cross-contamination around high-rise building.

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.