论文标题

关于一系列大规模蜿蜒的河流的形态动力学:通过将LES与沉积物 - 动力学耦合获得的见解

On the morphodynamics of a wide class of large-scale meandering rivers: Insights gained by coupling LES with sediment-dynamics

论文作者

Khosronejad, Ali, Limaye, Ajay B., Zhang, Zexia, Kang, Seokkoo, Yang, Xiaolei, Sotiropoulos, Fotis

论文摘要

在蜿蜒的河流中,流动,沉积物传输和床地图之间的相互作用会影响各种过程,包括床形发育和渠道迁移。预测这些相互作用如何影响蜿蜒的河流中床变形的空间模式和大小对于各种河流工程和地球科学问题至关重要。计算流体动力学仿真可以预测精细的时间和空间尺度上的河流动力学,但传统上受到大规模天然河流的挑战。我们进行了耦合的大涡模拟(LES)和床形态动力学模拟,以创建一个独特的数据库,用于4​​2个蜿蜒的河流,具有多种平面形状和大规模的几何特征,可模仿自然曲折。对于每条模拟河流,数据库包括(i)床形态,(ii)三维平均速度场和(iii)在河流流量条件下的床剪应力分布。在动态平衡处计算出的形态动力学结果,揭示了外部和内部库附近的冲刷和沉积模式的形成,而曲折弯曲的顶点周围的点杆和冲刷区的位置则发现与弯曲曲率的半径相差,弯曲率达到了宽度率。提出了一种新的机制,解释了这一看似自相矛盾的发现。这项工作中产生的高保真模拟结果为研究人员和科学家提供了丰富的数值数据库,用于大规模蜿蜒河流中的形态动力学和床剪应力分布,以实现对基本现象的系统研究并支持一系列河流工程应用。

In meandering rivers, interactions between flow, sediment transport, and bed topography affect diverse processes, including bedform development and channel migration. Predicting how these interactions affect the spatial patterns and magnitudes of bed deformation in meandering rivers is essential for various river engineering and geoscience problems. Computational fluid dynamics simulations can predict river morphodynamics at fine temporal and spatial scales but have traditionally been challenged by the large scale of natural rivers. We conducted coupled large-eddy simulation (LES) and bed morphodynamics simulations to create a unique database of hydro-morphodynamic datasets for 42 meandering rivers with a variety of planform shapes and large-scale geometrical features that mimic natural meanders. For each simulated river, the database includes (i) bed morphology, (ii) three-dimensional mean velocity field, and (iii) bed shear stress distribution under bankfull flow conditions. The calculated morphodynamics results at dynamic equilibrium revealed the formation of scour and deposition patterns near the outer and inner banks, respectively, while the location of point bars and scour regions around the apexes of the meander bends is found to vary as a function of the radius of curvature of the bends to the width ratio. A new mechanism is proposed that explains this seemingly paradoxical finding. The high-fidelity simulation results generated in this work provide researchers and scientists with a rich numerical database for morphodynamics and bed shear stress distributions in large-scale meandering rivers to enable systematic investigation of the underlying phenomena and support a range of river engineering applications.

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