The technique of using imposed turbulence in combination with a forced boundary layer in order to model the atmospheric boundary layer is analyzed for a very long domain using large‐eddy simulations with different combinations of prescribed velocity profiles and pregenerated turbulence fields based on the Mann model. The ambient flow is first studied in the absence of wind turbines. The velocity profiles undergo a transition throughout the domain with a velocity increase of 10% to 15% close to the ground far downstream in the domain. The turbulence characteristics close to the turbulence plane are, as expected, similar to those of the added Mann turbulence. The turbulence will then undergo a transition throughout the domain to finally reach a balance with the shear profile at a certain downstream distance. This distance is found to depend on the turbulence level of the added Mann turbulence planes. A lower Mann turbulence level generally results in a shorter “balancing” distance. Secondly, a row of 10 turbines is imposed in the simulations at different distances from the plane of turbulence in order to determine how the distance affects wake conditions and power production levels. Our results show that a “balancing” distance is needed between the turbulence plane and the first turbine in the row in order to ensure nonchanging ambient conditions throughout the turbine row. This introduces an increase in the computational costs. The computational cost for the forced boundary technique is normally lower compared with using precursor simulations, for longer domains; however, this needs to be verified further.

中文翻译：

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大范围内强迫边界层中强加湍流演化的大涡模拟

使用大涡流模拟，在规定的速度剖面和基于Mann模型的预生成湍流场的不同组合下，对非常长的域分析了将强湍流与强制边界层结合使用以对大气边界层建模的技术。首先在没有风力涡轮机的情况下研究环境流量。速度分布在整个区域内经历过渡，靠近区域下游的地面速度增加了10％至15％。正如预期的那样，靠近湍流平面的湍流特性类似于增加的曼湍流。然后，湍流将在整个区域内经历过渡，最终在一定的下游距离处与剪切剖面达到平衡。发现该距离取决于所添加的曼湍流平面的湍流水平。较低的Mann湍流水平通常会导致较短的“平衡”距离。其次，在模拟中将一排10台涡轮机施加在距湍流平面的不同距离处，以确定该距离如何影响尾流条件和发电水平。我们的结果表明，在湍流平面和排中的第一个涡轮之间需要一个“平衡”距离，以确保整个排中的环境条件不变。这导致计算成本的增加。对于较长的域，与使用前体模拟相比，强制边界技术的计算成本通常较低。但是，这需要进一步验证。