本研究利用大渦模擬方法，對地表粗糙度和森林對風力發電機尾流的影響進行了數值研究。在這項研究中，我們採用了由吳毓庭和 Fernando Porté-Agel 開發的大渦流模擬代碼的修改版本。我們選擇了一架入流速度為 9 公尺每秒的風力發電機，進行了在四種不同均勻平坦地表上的模擬，這些地表的粗糙度長度分別為5 × 10−1公尺、5 × 10−2公尺、5 × 10−3公尺及5 × 10−5公尺。在森林模擬中，我們使用了等效森林阻力數值模型，而不是幾何結構。森林被分為三個密度級別：稀疏、中等和密集，以及三個不同的高度水平：20 公尺、30 公尺和 40 公尺。我們對上述情景進行了模擬，並選擇了最具代表性的結果進行分析。分析了流向速度、速度耗散、紊流強度和動量通量等物理量。模擬結果表明，隨著尾流恢復過程的開始，森林對尾流的影響變得明顯。隨著森林密度和高度的增加，在風力發電機輪轂高度處，流向速度的恢復速率減慢，與入流相比紊流強度的增加更加明顯，並且與入流相比動量通量的減少更加顯著。此外，較平滑的地表條件通常會導致速度耗散增加、紊流強度增加、由於風力發電機引起的動量通量減少，以及風力發電機與最大動量通量位置之間的距離增大，森林對風力發電機尾流的影響變得更加明顯。總之，森林的存在會減緩風力發電機尾流的恢復過程

This study presents a numerical investigation of the effects of surface roughness and forests on wind-turbine wakes using a large-eddy simulation approach. In this research endeavor, we employed a modified version of the large-eddy simulation code developed by Yu-Ting Wu and Fernando Porté-Agel. A wind turbine with a constant inflow wind streamwise velocity of 9 ms−1 was selected for simulations conducted over four different homogeneous flat surfaces with surface roughness lengths of 5×10−1 ?, 5×10−2 ?, 5×10−3 ?, and 5×10−5 ?. For the forest simulations, we used an equivalent forest resistance numerical model rather than a geometric structure. The forests were categorized into three levels of density: sparse, moderate, and dense, and three different height levels: 20 m, 30 m, and 40 m. We simulated the aforementioned scenarios and selected the most representative results for analysis. Physical quantities such as streamwise velocity, velocity deficit, turbulence intensity, and momentum flux were analyzed. The simulation findings suggest that the impact of forests on the wake becomes apparent as the wake recovery process commences. As the forest density and height increase, the recovery rate of streamwise velocity at the wind turbine hub-height slows down, the augmentation of turbulence intensity in relation to the inflow becomes more pronounced, and the decrease in momentum flux relative to the inflow becomes more significant. Additionally, smoother surface conditions generally lead to increased velocity deficit, higher turbulence intensity, reduced momentum flux caused by the turbine, and a larger distance from the turbine to the location of maximum momentum flux happened, the impact of the forest on the wind-turbine wake becomes more pronounced. In summary, the presence of forests slows down the recovery of wind-turbine wakes.

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