The Impact of Flow Field and Diffusion by Roughness of Surface

• Main Authors: S. T. Guo, 郭世聰
• Other Authors: H. C. Chiang
• Format: Others
• Language: zh-TW
• Published: 1994
• Online Access: http://ndltd.ncl.edu.tw/handle/23732746015231350875

碩士 === 淡江大學 === 水資源及環境工程所 === 82 === The diffusion of air pollutants over complex terrain is affected by the complicated wind field generated by topography. Because it is very difficult to predict the wind field by simple mathematical model in complex terrain, wind tunnel experiments are widely used for this task in the past. The method used for constructing the physical models will affect the results wind tunnel experiments. In this study, the transport and diffusion of a pollutants near a three dimensional Gaussian hill is investigated. Three different methods were used to construct the models. The first models are "stepped" models constructed by Styrofoam with different thickness. The third model is also constructed by Styrofoam but its surface was smoothed by fill in. The flow field is measured by X-type hot film anemometers. The diffusion experiments have been simulated by SF6 which is measured by a ECD GC. From the results of experiments we found the wind field and concentration near ground surface were strongly affected by the surface roughness of the models, especially in the lee side of the hill.