都市建築區景觀排樹植栽對行人風場減風功效之探討

Numerical Investigation of Wind Reduction Effect of Row Trees in Urban Building Area

都市建築區中栽種景觀樹及行道樹除了有助於景觀之調和外，對於區內風場微氣候也能有相當程度之影響，並在多風區域行人風環境之改善上扮演著正面之角色。本研究以過往相關單株植栽模擬研究之成果為基礎，將風場數值模擬延伸到排樹情況地面風場之探討。研究中首先選定具有不同樹冠枝葉密度的典型樹種，並製作縮小尺度之樹模型，於風洞試驗中量得之樹後風速剖面乃成為後續風場模擬計算中律定樹冠枝葉特性參數之基準。待排樹鄰近風場的數值模式確立後，則藉由真實風域情況中樹種、樹高與樹間距之改變進行系統化的排樹風場模擬，繼而獲得這些因子對樹後行人高度範圍中減風效應的量化結果，以為排樹植栽減風設計規劃的重要參考。

 

Planting pedestrian trees in urban building areas can not only upgrade the landscape of the territories but affect the local micro-meteorology and lead to improvements of wind environment. The study is to investigate the wind reduction effect behind row trees so as to gain additional insight into the related landscape tree design. At the beginning, three typicaltree species with different clown densities are selected and the corresponding tree models are made. The wind speed profiles downstream of trees are measured and used as the basis to calibrate the corresponding characteristic clown parameters. After the numerical model is determined, a series of numerical computations are further performed in real prototype scales by varying the tree height and tree distance. The results of the wind field at the pedestrian level are then analyzed on a systematic basis to analyze quantitatively the effect of wind reduction and to assess the associated row-tree design principles.