Sensitivity analysis of wall-modeled large-eddy simulation for separated turbulent flow
Sensitivity analysis of wall-modeled large-eddy simulation for separated turbulent flow
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DOI：
10.1016/j.jcp.2024.112948
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发表时间：
2023-09
期刊：
影响因子：
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通讯作者：
Di Zhou;H. J. Bae
中科院分区：
文献类型：
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作者：
Di Zhou;H. J. Bae
在这项研究中，我们进行了参数分析，以评估壁面模型大涡模拟(LES)对亚网格尺度(SGS)模型、网格分辨率、壁面边界条件和网格各向异性的敏感性。虽然这类研究是针对附着流/平板流结构进行的，但专门针对具有分离的湍流的系统研究却非常稀少。为了弥补这一空白，我们的研究集中在中等高雷诺数的二维高斯型凸轮上的流动，其中包括在压力梯度和表面曲率效应下湍流边界层的光体分离。在模拟中，基于薄壁边界层方程和高保真数值模拟得到的平均壁面剪应力，用三种不同形式的边界条件代替了壁面处的无滑移条件，避免了模拟壁面剪应力的额外复杂性。对SGS模型的平均分离气泡尺寸、平均速度分布和耗散等统计数据进行了比较和分析。结果表明，分离气泡的捕获很大程度上依赖于SGS模型的选择。虽然模拟以接近壁面分辨大涡模拟网格的分辨率来逼近网格收敛，但高于这一限制，大涡模拟预报对网格分辨率表现出复杂的敏感性。此外，壁面边界条件和网格单元的各向异性对湍流预测都有明显的影响，但这些影响的大小取决于用于模拟的特定SGS模型。
In this study, we conduct a parametric analysis to evaluate the sensitivities of wall-modeled large-eddy simulation (LES) with respect to subgrid-scale (SGS) models, mesh resolution, wall boundary conditions and mesh anisotropy. While such investigations have been conducted for attached/flat-plate flow configurations, systematic studies specifically targeting turbulent flows with separation are notably sparse. To bridge this gap, our study focuses on the flow over a two-dimensional Gaussian-shaped bump at a moderately high Reynolds number, which involves smooth-body separation of a turbulent boundary layer under pressure-gradient and surface-curvature effects. In the simulations, the no-slip condition at the wall is replaced by three different forms of boundary condition based on the thin boundary layer equations and the mean wall-shear stress from high-fidelity numerical simulation to avoid the additional complexity of modeling the wall-shear stress. Various statistics, including the mean separation bubble size, mean velocity profile, and dissipation from SGS model, are compared and analyzed. The results reveal that capturing the separation bubble strongly depends on the choice of SGS model. While simulations approach grid convergence with resolutions nearing those of wall-resolved LES meshes, above this limit, the LES predictions exhibit intricate sensitivities to mesh resolution. Furthermore, both wall boundary conditions and the anisotropy of mesh cells exert discernible impacts on the turbulent flow predictions, yet the magnitudes of these impacts vary based on the specific SGS model chosen for the simulation.