基于计算力流体力学的城市近郊湖泊“冷岛效应”及其情景模拟研究——以长沙市同升湖为例

城市湖泊生态效益优越,对周围环境具有明显的“冷岛效应”。中尺度层面上,从环境物理学角度出发,以位于长沙市近郊区的同升湖作为研究对象,采用平行定点实测法获取夏季湖泊周边热环境指标,结合CFD情景模拟,二者交互验证。同时设置湖区周边近地面层典型气候边界条件,通过改变单一影响因子的变化,系统分析了夏季城市近郊湖泊“冷岛效应”的变化规律以及湖区周边建筑对湖泊“冷岛效应”发挥的影响,揭示了湖泊与周围环境之间的温度交互特征。结果表明:(1)夏季城市近郊湖泊对周围环境存在“冷岛效应”,研究区域与对照区域的日均温度差值在0.55℃,湖泊“冷岛效应”的发挥与太阳辐射强度相关,在13:00—14:00时间段内较突出;(2)湖泊“冷岛效应”与临湖距离呈显著负相关,湖泊水体的降温作用在0 m处最显著,在距湖岸300 m范围明显,在距湖岸600 m范围存在降温作用,湖泊水体对主导风下风向区域的降温效果最佳,降温强度可达0.96℃;(3)通过改变单一影响因子的CFD情景模拟发现,湖泊“冷岛效应”发挥与建筑高度、建筑后退湖岸距离、建筑间距密切相关,建筑后退湖岸100 m和200 m,下风向区域温度降低0.34—0.56℃,降温范围在650—800 m;建筑高度增加10 m和20 m,下风向区域温度上升0.09—0.39℃,降温范围在350—500 m;建筑间距增大2倍,下风向区域温度下降0.27℃左右,降温范围在500—600 m。该研究成果对研究城市湖泊小气候、改善城市局域热环境及指导未来城市近郊湖区建设布局具有重要指导意义。

ADSORPTION CHARACTERISTICS OF SACFs FORA VARIETY OF DYES

The isothermal adsorption of dyes on a variety of sisal based activated carbonfibers (SACFs), and the influence of PH and temperature on absorption are discussedin this paper The results indicate that the adsorption of methylene blue, crystal violetand Eriochrome blue black R on SACFs shows type I isotherms and can be describedby the Langnuir equation or the Freudlich equation. The acidity of solution hasgreatly ifluence over the adeorption amounts of methylene blue, crystal violet andEriochrome blue black R. As PHs of the solutions were adjusted to increase ordecrease from the original acidity of the solution (4. 7. 4. ) and 4. 0 for methylene blue,crystal violet and Eriochrome blue black R. respectively), the amounts of dyesadsorbed on SACFs increased. The adsorption temperature (in the range of 25~50℃)exerts little influence on the adsorption amount of methylene blue, crystal violet andfluorescein. For azo dyes (Eriochrome blue black R and Eriochrome black T), howeverthe absorption amount increases slightly with the elevation of temperature.