本文主要目的是要了解水流經過植被之水動力特性，採用計算流體力學模式模擬水流通過剛體圓柱植被的流動過程。本研究利用 Fluent 軟體中的大渦流模擬模式進行運算，與 Liu et al. (2008) 之實驗結果進行比對，探討亞網格應力模式之 Smagorinsky-Lilly 模式中的 Cs 值的敏感度。當 Cs 值設定為0.1時，水平速度與垂直速度與實驗值最為接近。模擬結果顯示，當水流經過圓柱植被後，會產生渦流及回流之現象，水平速度在植被附近的流動類似於一個具有速度分佈轉折點的混合層，垂直速度在靠近植物頂部的位置會出現向下，表示後方產生渦流造成流體往下帶的結果。 The purpose of this paper is to investigate the hydrodynamic characteristics of flow through the submerged vegetation. Large eddy simulation model in Fluent is applied to present the processes of flow through the rigid cylindrical vegetation. A parameter in the subgrid-scale stresses Smagorinsky-Lilly model, Smagorinsky constant Cs, is calibrated with the laboratory experimental data. Cs values. With the optimal value of 0.1, model results show that horizontal velocity and vertical velocity are in good agreement with the measurements. The phenomenon of vortex and reflux are exhibited behind the cylinder vegetation. Additionally, horizontal velocity profile with an inflection point in the vicinity of the vegetation which resembles a mixing layer. The fluid flows downward behind the vegetation due to vortices generated on the vegetation top.
