Random Force Perturbations: A New Extension of the Cell Perturbation Method for Turbulence Generation in Multiscale Atmospheric Boundary Layer Simulations
Random Force Perturbations: A New Extension of the Cell Perturbation Method for Turbulence Generation in Multiscale Atmospheric Boundary Layer Simulations
复制标题
随机力扰动：多尺度大气边界层模拟中湍流生成的单元扰动方法的新扩展
DOI：
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发表时间：
2019
影响因子：
6.8
通讯作者：
R. Linn
中科院分区：
文献类型：
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作者：
L. Mazzaro;E. Koo;D. Muñoz‐Esparza;J. Lundquist;R. Linn
中尺度和大涡模拟(LES)之间的耦合对于从风能预报到火灾传播的许多大气模式应用都是至关重要的。网格嵌套技术可以在巨大不同的尺度之间架起桥梁，而不会招致高昂的计算成本。然而，从较粗的分辨率到较细的分辨率的转变通常需要从流入边界的大量网格点来发展LES区域中的细尺度湍流特征。近年来，细胞摄动法(CPM)被用来缩小湍流发展区，具有很高的计算效率。在此，我们探索了一种基于CPM的新方法(力胞摄动法)，该方法利用水平和垂直方向的力摄动来代替原来的CPM中的势温摄动，以进一步探索随机摄动技术的性能。在理想条件下，对中性大气边界层和对流大气边界层进行了试验。总体而言，CPM的最优构型与力单元摄动法的性能相似，表明这一族摄动法在加速嵌套区域内的湍流生成方面具有较强的稳健性。在两种大气稳定条件下，垂直力摄动都比水平力摄动表现得更好。CPM在对流稳定条件下表现最好。与单独应用单独的方法相比，力和潜在温度扰动的组合并不能提供额外的性能改进。
Coupling between mesoscale and large eddy simulation (LES) is critically important for many atmospheric model applications, from predictions of wind energy to fire propagation. The grid‐nesting technique enables bridging between vastly different scales without incurring prohibitive computational costs. However, the transition from coarser to finer resolutions often requires a large number of grid points from inflow boundaries for the development of fine‐scale turbulence features in the LES domain. Recently, the cell perturbation method (CPM) was developed to reduce the turbulence development region with high computational efficiency. Herein, we explore a new method based on the CPM that uses force perturbations in both the horizontal and vertical directions (Force Cell Perturbation Method) instead of the potential temperature perturbations in the original CPM, as an attempt to further explore the performance of the random perturbation techniques. This approach is tested for a neutral and a convective atmospheric boundary layer under idealized conditions. Overall, similar performance is found between the optimal configurations of the CPM and the Force Cell Perturbation Method pointing to the robustness of this family of perturbation methods in accelerating turbulence generation in nested domains. Vertical force perturbations performed better than horizontal force perturbations for both atmospheric stability conditions. The CPM performed best under convective stability conditions. The combination of the force and potential temperature perturbations is found to provide no additional performance improvement over the stand‐alone application of the individual methods.