本研究使用開源軟體OpenFOAM 模擬大氣邊界層流動，將會依序介紹流場初始條件、邊界條件與源項之設定，並且選擇 LES 模型中的WALE model 與 Smagorinsky model 作為紊流模型，將二者結果相互比較之外，也與前人使用Ansys Fluent之研究成果做比對。主要觀察的結果為幾項紊流特性，分別為半對數尺度之無因次化平均流向速度，平均速度、動量通量、紊流強度隨垂直高度之變化以及功率頻譜。
雖然本研究之成果沒有達到預期的趨勢，但是可以發現WALE model 在壁面附近的渦流行為表現較Smagorinsky model 敏感，再來，地面的邊界條件需要再嘗試其他類型的邊界，目前設置的邊界為無滑移條件（no-Slip），模擬結果不如預期，所以開始尋找相關資料查看可能的原因後，發現也許可以利用剪應力邊界的效應，去達成紊流接近地面時，會是存在擾動量且數值是較大的情況，在套裝軟體中，有圖形介面明確顯示輸入剪應力數值之位置，可以是常數之數值，也可以是自行撰寫程式後匯入軟體內。最後， OpenFOAM計算的時間比套裝軟體快約兩倍以上的時間，因為在套裝軟體有圖形介面之關係，會影響模擬計算之速度。在此之後，套裝軟體和OpenFOAM進行模擬之選擇時，若需要盡快研究結果的話，可以選擇OpenFOAM作為執行模擬的軟體。

In this study, the open source software OpenFOAM is used to simulate the flow of the atmospheric boundary layer. The initial conditions, boundary conditions and source terms of the flow field will be introduced in sequence, and the WALE model and the Smagorinsky model in the LES model will be selected as the turbulence models, and the results of the two will be used. In addition to comparing with each other, it is also compared with the previous research results using Ansys Fluent. The main observed results are several turbulent characteristics, namely, dimensionless mean flow velocity on a semi-log scale, mean velocity, momentum flux, turbulence intensity versus vertical height, and power spectrum.
Although the results of this study didn’t meet the expected trend, it can be found that the vortex behavior of the WALE model near the wall is more sensitive than the Smagorinsky model. Furthermore, the boundary conditions of the ground need to try other types of boundaries. The boundary currently set is no-slip The simulation result is not as expected, so after starting to look for the relevant data to check the possible reasons, it is found that the effect of the shear stress boundary may be used to achieve the turbulent flow close to the ground, there will be a disturbance and the value is In larger cases, in the packaged software, there is a graphical interface that clearly displays the position of the input shear stress value, which can be a constant value, or it can be imported into the software after writing a program by itself. Finally, the calculation time of OpenFOAM is about twice faster than that of the package software, because the relationship between the graphical interface in the package software will affect the speed of simulation calculation. After that, when choosing between the package software and OpenFOAM for simulation, if you need to study the results as soon as possible, you can choose OpenFOAM as the software to perform the simulation.

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