Abstract Recent numerical predictions of turbulent boundary layers subject to very strong Favorable Pressure Gradient (FPG) with high spatial/temporal resolution, i.e. Direct Numerical Simulation (DNS), have shown a meaningful weakening of the Reynolds shear stresses with a lengthy logarithmic behavior [1,2]. In the present study, assessment of the Shear Stress Transport and Spalart-Allmaras turbulence models (henceforth SST and SA, respectively) in Reynolds-averaged Navier-Stokes (RANS) simulations is performed. The main objective is to evaluate the ability of popular turbulence models in capturing the characteristic features present during the quasi-laminarization phenomenon in highly accelerating turbulent boundary layers. A favorable pressure gradient is prescribed by a top converging surface (sink flow) with an approximately constant acceleration parameter of K = 4.0 × 10 − 6 . Validation of RANS results is carried out by means of a large DNS dataset [1]. Generally speaking, the SA turbulence model has demonstrated the best compromise between accuracy and quick adaptation to the turbulent inflow conditions. Turbulence models properly captured the increasing trend of the freestream and friction velocity in highly accelerated flows; however, they fail to reproduce the decreasing behavior of the skin friction coefficient, which is typical in early stages of the quasi-laminarization process. Both models have shown deficient predictions of the decreasing and logarithmic behavior of Reynolds shear stresses as well as significantly overpredicted the production of Turbulent Kinetic Energy (TKE) in turbulent boundary layers subject to very strong FPG.

中文翻译：

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受强有利压力梯度影响的湍流边界层中的雷诺剪应力建模

摘要 受具有高空间/时间分辨率的非常强的有利压力梯度 (FPG) 影响的湍流边界层的最新数值预测，即直接数值模拟 (DNS)，已显示雷诺剪切应力的显着减弱和长期对数行为 [1] ,2]。在本研究中，在雷诺平均 Navier-Stokes (RANS) 模拟中对剪切应力传输和 Spalart-Allmaras 湍流模型（以下分别称为 SST 和 SA）进行了评估。主要目标是评估流行的湍流模型在捕捉高度加速湍流边界层准层化现象期间存在的特征特征的能力。有利的压力梯度由顶部会聚表面（汇流）规定，其加速度参数近似恒定为 K = 4.0 × 10 - 6 。RANS 结果的验证是通过大型 DNS 数据集进行的 [1]。一般来说，SA 湍流模型已经证明了对湍流流入条件的准确性和快速适应之间的最佳折衷。湍流模型正确地捕捉了高度加速流动中自由流和摩擦速度的增加趋势；然而，它们无法重现皮肤摩擦系数的降低行为，这是准层化过程早期阶段的典型特征。