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標題: 建築物下洗現象對高斯煙流軌跡模式於污染物模擬之影響探討
Inplementation of building downwash effects for a Gaussian trajectory Model
作者: 蔡郅隆
Tsai, Chih-Lung
關鍵字: GTx;高斯煙流軌跡模式;Building downwash;cavity;煙流下洗現象;空穴
出版社: 環境工程學系
許多研究顯示挾帶污染物的氣流在通過建築物時會發生分離流的現象,由於氣流的分離作用,在建築物的下風處形成一個空穴(cavity),其對上風處煙柱的擴散作用將產生干擾抑制現象。因此高濃度污染物會累積在建築物背面的空穴區內。由此可知,建築物的煙流下洗現象(Building downwash)對於模式在模擬污染物擴散及濃度累積方面有舉足輕重的影響。
本研究使用Schulman and Scire之建築物下洗計算方式,將下洗機制程式化加入GTx模式中,觀察其對模式之影響,並對照此參數模組加入前後對模擬結果的差異,探討其相關性,期使GTx模式的模擬有更加準確及合理的結果。本研究預計對於一座焚化爐及一座集塵灰煉鋼廠所排放之戴奧辛(dioxins)做相關之模式模擬。模擬的結果,建築物下洗現象對GTx模式的主要影響在增加排放源鄰近地區的地面污染物濃度。

It generally used air quality models, meteorology models and Gaussian Trajectory models such as Gaussian Trajectory transfer-coefficient modeling system (GTx) cooperating with the meteorological data to simulate the trajectory of the pollutants and meteorological phenomena in the neighborhood of the emission source while sampling. In addition, investigated the variations of the pollutants and their origins by drawing pollutant concentration illustrations and simulated trajectory illustrations. Furthermore, analyzed the effects to the neighbor area of the pollution source and the accumulated concentration.
Many researches indicated that separated flows occured when airstreams of pollutants passed through buildings. Due to the separated flows, a cavity which interfered and restrained the plume dispersion formed in the lee of the building. Thereby, it lowered the plume height and tended to accumulate a great deal of pollutants in the cavity of the back of the building. Thus it can be seen, building downwash played an important role in modeling the dispersion and concentration of the pollutants.
The aim of the study was to investigate the inplementation of building downwash effects for a Gaussian Trajectory model and compare the similarity and dissimilarity of the simulated results. This study was expected to proceed some simulations and analyses to several incinerators and steel-smelting furnaces. The result of the simulations showed that the main influence of the building downwash phenomenon in GTx was to increase the ground-level concentration of pollutants in the neighborhood of the emission source.
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