We found a match
Your institution may have access to this item. Find your institution then sign in to continue.
- Title
On the Morphodynamics of a Wide Class of Large‐Scale Meandering Rivers: Insights Gained by Coupling LES With Sediment‐Dynamics.
- Authors
Khosronejad, Ali; Limaye, Ajay B.; Zhang, Zexia; Kang, Seokkoo; Yang, Xiaolei; Sotiropoulos, Fotis
- Abstract
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 and bed morphodynamics simulations to create a unique database of hydro‐morphodynamic data sets 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 (a) bed morphology, (b) three‐dimensional mean velocity field, and (c) 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. Plain Language Summary: River flows in nature follow spectacular meandering paths from upstream to downstream. Such flows are turbulent and interact with mobile sediment and the shape of the channel through an intricate set of complex feedback mechanisms that impact flow dynamics, sediment motion, and streambank stability leading to migration of river dunes and erosion of the channel banks. Computer models are key tools for understanding these mechanisms but have traditionally faced challenges in representing turbulent flow at the scales of natural rivers. We generated 42 synthetic, meandering rivers with various geometrical and flow characteristics representative of those encountered in nature. We then simulate numerically the flow over the mobile bed for each of these rivers to predict changes in the bed geometry. We analyze the predicted results to determine general trends in the predicted shape of the riverbed and the distribution of shear stresses near the riverbed. The resulting library of simulation results provides a data set of unprecedented resolution and detail for a wide class of river meanders encountered in nature enabling engineers and scientists to develop a predictive understanding of river morphodynamics to develop mathematical approaches for river restoration, and infrastructure design and protection against floods. Key Points: A series of large‐scale river meanders with various geometries and flow characteristics were simulated to represent natural meandersThe bed deformation of the meanders was obtained using a coupled hydro‐ and morpho‐dynamic model under bankfull flow conditionsBy analyzing the morphodynamic simulation results of the meanders, general trends in bed deformations and bed shear stress were found
- Subjects
MEANDERING rivers; COMPUTATIONAL fluid dynamics; SHEAR (Mechanics); SHEARING force; RIVER engineering
- Publication
Journal of Advances in Modeling Earth Systems, 2023, Vol 15, Issue 3, p1
- ISSN
1942-2466
- Publication type
Article
- DOI
10.1029/2022MS003257