摘要
本文采用数值模拟技术对日光照射街道峡谷地面时峡谷内气体运动和机动车排放污染物扩散规律进行了研究。研究结果表明当日光照射到地面时,使得地面与峡谷内空气产生温差,由于密度不同造成的浮升力会对街道峡谷内的流场产生影响:风速较大时,峡谷内依然是规则的漩涡结构,热效应增强了湍流强度;风速较小时,峡谷内的流场结构发生变化,由较强的单漩涡变为多漩涡结构,与不计日光照射时峡谷内运动特征有显著的不同。峡谷内的污染物扩散受到流场结构变化的影响,在迎风面一侧逆时针漩涡的作用下污染在迎风面产生积累,而且多漩涡流场结构使峡谷内污染物浓度升高;但随着温差的增大,峡谷内的运动增强,污染物浓度相应降低。
Urban street canyon flows in the presence of bottom heating are investigated using a two-dimensional numerical model with a k-ε turbulence model. The simulations show that when the wind speed is slow the bottom heating can have important effects on the flow regime, an upward buoyancy flux created a distinctive effect on the mail flow, thereby dividing the flow structure into two contra-rotating cells. As the result, the higher concentration may appear on the windward face than on the leeward face. On the contrary, when the wind speed is high or there is no heating, there is a unique vortex in the street canyon, the higher concentration may appear on the leeward face than on the windward face. It is concluded that the temperature different range and the wind speed are same important for the thermal effects in street canyon.
出处
《水动力学研究与进展（A辑）》
CSCD
北大核心
2004年第z1期865-870,共6页
Chinese Journal of Hydrodynamics
基金
通用中国发展与研究基金(40122201)
国家自然科学基金(50208011)
