Abstract This paper proposes a Computational Fluid Dynamics (CFD) framework with the aim of combining consistency and efficiency for the numerical simulation of high Reynolds number flows encountered in engineering applications for aerodynamics. The novelty of the framework is the combination of a Reynolds-Averaged Navier–Stokes (RANS) model with an anisotropic mesh adaptation strategy handling arbitrary immersed geometries by building the corresponding boundary layer meshes. The numerical algorithm consists of robust and accurate solution of the unsteady incompressible Navier–Stokes equations supplemented with a Spalart–Allmaras turbulence model and boundary layer remeshing relying on a specifically designed metric. The flow solver is formulated as a Variational Multiscale (VMS) finite element method for the momentum balance and the incompressibility constraint, and as an upwind Petrov–Galerkin method for the nonlinear turbulent equation. The boundary layer remeshing strategy is flexible as it allows the adaptation of arbitrary coarse meshes by modifying the size and the orientation of elements along the immersed boundary to ensure a smooth gradation along the curvature of the body's geometry. The solver is capable of handling highly stretched anisotropic elements and is shown to successfully predict both mean and fluctuating drag/lift coefficients. Laminar and turbulent test cases in 2D and 3D are presented to assess the performance of this framework against experimental results relevant to external aerodynamics, including an airship and a flying drone.

中文翻译：

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用于可靠 3D 非稳态 RANS 模拟的各向异性边界层网格生成

摘要 本文提出了一种计算流体动力学 (CFD) 框架，旨在结合一致性和效率，对空气动力学工程应用中遇到的高雷诺数流动进行数值模拟。该框架的新颖之处在于将雷诺平均纳维-斯托克斯 (RANS) 模型与各向异性网格自适应策略相结合，通过构建相应的边界层网格来处理任意浸入几何。数值算法包括非定常不可压缩 Navier-Stokes 方程的稳健和精确解，辅以 Spalart-Allmaras 湍流模型和依赖于专门设计的度量的边界层重新网格划分。流动求解器被公式化为用于动量平衡和不可压缩约束的变分多尺度 (VMS) 有限元方法，以及用于非线性湍流方程的逆风 Petrov-Galerkin 方法。边界层重新网格划分策略是灵活的，因为它允许通过沿浸入边界修改元素的大小和方向来适应任意粗网格，以确保沿主体几何曲率的平滑渐变。该求解器能够处理高度拉伸的各向异性元素，并显示成功预测平均和波动的阻力/升力系数。提出了 2D 和 3D 中的层流和湍流测试案例，以根据与外部空气动力学相关的实验结果（包括飞艇和飞行无人机）评估该框架的性能。