Study on Atmospheric Environment Around River

夏季河流对河流周围大气温度的降温作用在定性方面是众所周知的现象，但在定量方面却不为人所知。为了定量评价，描述动量和热量传递过程的物理模型是必要的。为了构建模型，观测了渡濑河和九龙河附近的风速、温度和湿度。河面温度较城区低2 ~ 3℃。垂直方向的湍流热扩散系数为10^<-1> m^2/sec数量级。除上述观察外，还在90 × 90 cm横截面的风洞中进行了一些实验。采用长方管（横截面为12.5x8 cm）模拟河道，管内设置干冰作为冷却源。该管道两侧，保温材料覆盖人造草坪作为表面粗糙度，安装为河边区域。用二维热膜风速仪测量了风速。结合实验冷却条件和风速条件，分析了雷诺数应力和涡流粘度值的变化及其廓线。

The cooling effect of river on atmospheric temperature around rever in summer is a well known phenomenon in qualitative respect, but not in a quantitative respect. To evaluate quantitatively, the physical model describing the transport process of momentum and heat is necessary. For construction of the model, wind velocity, temperature and humidity were observed around River Watarase and River Kyuryu. The temperature of river side was 2-3 ﾟC lower to compared to urban area. The turblence thermal diffusion coefficient of vertical direction was order of 10^<-1> m^2/sec. In addition to observations described above, some experiments were carried out in wind tunnel having 90x90 cm cross section. A river channel is simulated by a long square pipe (12.5x8 cm cross section), and dry ice was set inside of this pipe as cooling source. Both side of this pipe, heat insulating material covered with artificial lawn as surface roughness were installed as river side area. Wind velocity was measured with 2- dimensional hot-film anemometer. Change of value of Reynolds stress and eddy viscosity, and of their profiles were analyzed in combination with experimental conditions of cooling and wind velocity.