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Unsteady shallow meandering flows in rectangular reservoirs: A modal analysis of URANS modelling
Journal of Hydro-environment Research ( IF 2.8 ) Pub Date : 2022-03-25 , DOI: 10.1016/j.jher.2022.03.002
Daniel Valero , Daniel B. Bung , Sebastien Erpicum , Yann Peltier , Benjamin Dewals

Shallow flows are common in natural and human-made environments. Even for simple rectangular shallow reservoirs, recent laboratory experiments show that the developing flow fields are particularly complex, involving large-scale turbulent structures. For specific combinations of reservoir size and hydraulic conditions, a meandering jet can be observed. While some aspects of this pseudo-2D flow pattern can be reproduced using a 2D numerical model, new 3D simulations, based on the unsteady Reynolds-Averaged Navier-Stokes equations, show consistent advantages as presented herein. A Proper Orthogonal Decomposition was used to characterize the four most energetic modes of the meandering jet at the free surface level, allowing comparison against experimental data and 2D (depth-averaged) numerical results. Three different isotropic eddy viscosity models (RNG k-ε, k-ε, k-ω) were tested. The 3D models accurately predicted the frequency of the modes, whereas the amplitudes of the modes and associated energy were damped for the friction-dominant cases and augmented for non-frictional ones. The performance of the three turbulence models remained essentially similar, with slightly better predictions by RNG k-ε model in the case with the highest Reynolds number. Finally, the Q-criterion was used to identify vortices and study their dynamics, assisting on the identification of the differences between: i) the three-dimensional phenomenon (here reproduced), ii) its two-dimensional footprint in the free surface (experimental observations) and iii) the depth-averaged case (represented by 2D models).



中文翻译:

矩形油藏中的非定常浅曲折流:URANS 建模的模态分析

浅水流在自然和人造环境中很常见。即使对于简单的矩形浅层油藏,最近的实验室实验表明,发展中的流场特别复杂,涉及大规模的湍流结构。对于储层大小和水力条件的特定组合,可以观察到蜿蜒的射流。虽然可以使用 2D 数值模型再现这种伪 2D 流动模式的某些方面,但基于非定常雷诺平均 Navier-Stokes 方程的新 3D 模拟显示出如本文所述的一致优势。使用适当的正交分解来表征自由表面水平上蜿蜒射流的四种最有活力的模式,从而可以与实验数据和 2D(深度平均)数值结果进行比较。k-ε , k-ε , k-ω ) 进行了测试。3D 模型准确地预测了模式的频率,而模式的幅度和相关能量在以摩擦为主的情况下被阻尼,而在非摩擦情况下则被增强。三种湍流模型的性能基本保持相似,在雷诺数最高的情况下, RNG k-ε模型的预测略好。最后,Q 准则用于识别涡旋并研究它们的动力学,有助于识别以下之间的差异:i)三维现象(此处复制),ii)其在自由表面的二维足迹(实验观察)和iii)深度平均情况(由二维模型表示)。

更新日期:2022-03-25
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