Resolution-induced anisotropy in large-eddy simulations
Resolution-induced anisotropy in large-eddy simulations
复制标题
DOI：
10.1103/physrevfluids.4.114605
复制
发表时间：
2019-11-13
影响因子：
2.7
通讯作者：
Moser, Robert D.
中科院分区：
文献类型：
--
作者：
Haering, Sigfried W.;Lee, Myoungkyu;Moser, Robert D.
复杂几何和区域湍流的大涡模拟（LES）通常使用不同形状和方向的高纵横比分辨率单元进行。这种各向异性分辨率的影响在子网格模型公式中往往被简化或忽略。在这里，我们研究了分辨率诱导的各向异性，并证明即使对于各向同性湍流，各向异性分辨率在二阶分辨速度梯度统计中也会引起轻微的分辨雷诺应力各向异性和显著的各向异性。在具有各向异性分辨率的均匀各向同性湍流的大涡模拟中，表明常用的子网格模型，包括那些在其公式中考虑分辨率各向异性的模型，表现不佳。唯一的例外是Rozema等人提出的各向异性最小耗散模型。[j].中国生物医学工程学报，2016,27(5):555 - 557。这里提出了一个简单的模型，它是Carati等人的“Kolmogorov表达式”涡旋粘度的各向异性涡旋扩散系数的扩展[大涡旋模拟的一系列动态模型，见《年度研究简报》，湍流研究中心（斯坦福大学和NASA AMES， 1995），第35-40页]，它明确地取决于分辨率的各向异性。与其他LES子网格模型不同，它的表现也很好，而且值得注意，因为涡旋扩散率只取决于湍流的统计特征（在这种情况下是耗散率），而不取决于波动量。在其他子网格建模公式中，例如动态过程，以这种方式将流量依赖于统计量可能具有优势。
Large-eddy simulation (LES) of turbulence in complex geometries and domains is often conducted with high-aspect-ratio resolution cells of varying shapes and orientations. The effects of such anisotropic resolution are often simplified or neglected in subgrid model formulations. Here, we examine resolution-induced anisotropy and demonstrate that even for isotropic turbulence, anisotropic resolution induces mild resolved Reynolds stress anisotropy and significant anisotropy in second-order resolved velocity gradient statistics. In large-eddy simulations of homogeneous isotropic turbulence with anisotropic resolution, it is shown that commonly used subgrid models, including those that consider resolution anisotropy in their formulation, perform poorly. The one exception is the anisotropic minimum dissipation model proposed by Rozema et al. [Phys. Fluids 27, 085107 (2015)]. A simple model is presented here that is an anisotropic eddy diffusivity extension of the "Kolmogorov expression" eddy viscosity of Carati et al. [A family of dynamic models for large-eddy simulation, in Annual Research Briefs, Center for Turbulence Research (Stanford University and NASA AMES, 1995), pp. 35-40] that depends explicitly on the anisotropy of the resolution. It also performs well and is remarkable because, unlike other LES subgrid models, the eddy diffusivity only depends on statistical characteristics of the turbulence (in this case, the dissipation rate), not on fluctuating quantities. In other subgrid modeling formulations, such as the dynamic procedure, limiting flow dependence to statistical quantities in this way could have advantages.