Accurately modeling the hydrodynamics of submerged canopies is crucial for predicting sediment dynamics and geomorphodynamics. This paper introduces vortex-based Spalart–Allmaras (VBSA) models, considering the spatial structure of canopy-scale vortices and stem wakes. The VBSA models are innovative in incorporating the physics of canopy-overflow interaction. They were validated using experimental data across a wide range of velocities and canopy densities, and their performance was compared with other turbulence models (i.e., previous SA models and model). Despite lacking high-order numerical schemes, the VBSA models outperform other turbulence models, exhibiting less numerical dissipation and better replication of mean velocity and Reynolds shear stress profiles in the vortex penetration space and below the surface. A sensitivity analysis was conducted to identify optimal values for new model parameters. Analyses suggest that the porous canopy layer suppresses the mixing efficiency by reducing the turbulence length scale. The analysis of eddy viscosity flux balance reveals that the eddy viscosity is transferred to the canopy layer from the overflow by the canopy-scale vortices and is destructed in the canopy, with production being less important, particularly in large submergence scenarios.

中文翻译：

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使用基于涡流的 Spalart-Allmaras 模型改进水下冠层流的建模


准确模拟水下冠层的流体动力学对于预测沉积物动力学和地貌动力学至关重要。本文介绍了基于涡旋的 Spalart-Allmaras (VBSA) 模型，考虑了冠层尺度涡旋和茎尾流的空间结构。 VBSA 模型在结合树冠-溢出相互作用的物理原理方面具有创新性。使用各种速度和冠层密度的实验数据对它们进行了验证，并将它们的性能与其他湍流模型（即以前的 SA 模型和模型）进行了比较。尽管缺乏高阶数值方案，VBSA 模型的性能优于其他湍流模型，表现出较少的数值耗散以及更好地复制涡穿透空间和表面以下的平均速度和雷诺剪应力分布。进行敏感性分析以确定新模型参数的最佳值。分析表明，多孔冠层通过减小湍流长度尺度来抑制混合效率。涡粘性通量平衡分析表明，涡粘性通过冠层尺度涡从溢流转移到冠层，并在冠层中被破坏，其产生不太重要，特别是在大面积淹没的情况下。