由於綠色能源對風工程應用的需求越來越普遍，而風工程應用皆在大氣邊界層內，因此針對大氣邊界層的研究是必需的。本研究利用不同的數值模擬方式模擬大氣邊界層流流經均質地表，從而探討不同數值方法模擬出的結果和大氣邊界層理論進行比較。我們應用ANSYS FLUENT 商用軟體和In-house LES Framework並且選用大渦旋模擬(Large-Eddy Simulation)紊流模型來完成本次研究。
大渦旋模擬(LES)是一套很適用於大氣邊界層模擬的模型，其概念
是建立在「紊流的流動是由許多大小不同尺度的渦旋組成。大尺度的渦旋對平均流動影響較大，而小尺度的渦旋主要影響耗散項，通過耗散變動來影響各種變化。」LES的精確度僅取決於網格大小與Subgrid-scale model。它可以解析流場中大於網格的所有渦流，只有小於網格大小的渦流被參數化，並且，它可以預測紊流流體中的瞬時行為。
在FLUENT的模擬中我們使用兩種不同的壁面邊界條件: (1)無剪應力的靜止壁面和(2)使用者定義的特定剪應力條件，這兩種邊界條件會產生兩種不同的表面粗糙度，我們針對這兩種結果進行討論。在近地表區域，FLUENT的主流流向速度和速度變化量皆有低估的現象，但從速度頻譜圖上可以看出模擬結果在慣性次段(Inertial subrange)內的頻譜斜率接近-5/3，這和理論預測的斜率相當接近，因此此模擬結果是可信賴的。
在In-house LES Framework配合尺度依賴動態模型的模擬中，模擬結果顯示大部分的紊流特徵都和理論有相當高的一致性，因此這個模組在模擬大氣邊界層是非常適用的，也具有一定的準確性。

Due to increasing demands for wind energy applications, the investigations of wind data in atmospheric boundary layer have become essential. In this study, the flow data were computed from different numerical approaches. The approaches include the commercial package ANSYS Fluent and the pseudo-spectrum in-house code. The LES (Large-Eddy Simulation) turbulence closures were applied in our atmospheric boundary layer simulations.
LES is a powerful tool to simulate atmospheric turbulence. It contains the advantages that all of the components are solved in flow field but only the small scales require modeling. LES is available to predict instantaneous turbulent behavior in turbulent flows. In brief, the principle idea behind LES is to reduce computational cost and improve accuracy and authenticity in the turbulent flows.
There are two different wall boundary conditions used in the Fluent simulations: (a) stationary wall with no shear condition and (b) specified shear stresses based on Monin-Obukhov similarity theory, which carried out two different roughness lengths.
In the near-surface region, the streamwise velocity and velocity variance results obtained from the Fluent were underestimated, but the velocity spectra yielded a reliable agreement with theory. Compared to the results obtained from the Fluent, the in-house code based on the pseudo-spectrum method showed better agreement with the theory in all turbulence statistics.

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