Review and Comparison of Numerical Simulations of Secondary Flow in River Confluences

Abstract

River confluences are a common feature in natural water resources. The flow characteristics in confluences are complicated, especially at junction areas between tributaries and the main river. One of the typical characteristics of confluences is secondary flow, which plays an important role in mixing, velocity, sediment transport, and pollutant dispersion. In addition to the experimental and field studies that have been conducted in this area, the development of computational fluid dynamics has allowed researchers in this field to use different numerical models to simulate turbulence properties in rivers, especially secondary flows. Nowadays, the hydrodynamics of flows in confluences are widely simulated by using three-dimensional models in order to fully capture the flow structures, as the flow characteristics are considered to be turbulent and three-dimensional at river junctions. Several numerical models have been recommended for this purpose, and various turbulence models have been used to simulate the flows at confluences. To assess the accuracy of turbulence models, flows have been predicted by applying different turbulence models in the numerical model and the results have been compared with other data, such as field, laboratory, and experimental data. The purpose behind these investigations was to find the suitable model for each case of turbulent flow and for different types of confluences. In this study, the performances of turbulence models for confluences are reviewed for different numerical simulation strategies.

Experimentation, modelling, and simulation of hydrochory in an Amazonian river

“…An interesting aspect of the dispersal process is that the simulated CM transport showed a greater difference starting in the DFA03 section, probably influenced by the lateral forces of the discharge from the Braço Creek. Such behaviour was also registered in previous studies (Shaheed et al, 2021; Weber et al, 2001), which demonstrate the influence of tributaries in the seed dispersal by water. Furthermore, local geomorphology is important in the generation of secondary currents (helical flows).…”

“…Besides that, the wind may have contributed significantly to the difference between the results observed in the field and the simulation ones because wind speed variable held constant in the model. For instance, wind tends to flow preferentially along the longitudinal corridors of the streams following the topography of the local channel and the morphology of the riparian crowns (Groves et al, 2009; Parolin et al, 2013; Shaheed et al, 2021; Shi et al, 2020). This fact may partly explain why the observed plume flowed faster than the simulated plume.…”

Computational Fluid Mechanics and Hydraulics

“…This Special Issue includes eleven original contributions, including nine research articles [1][2][3][4][5][6][7][8][9] and three review papers [10,11]. In terms of the modeling techniques, these papers develop and apply a variety of methods such as mesh-based Eulerian [1][2][3], meshfree Lagrangian [4,5,7,8], and data-driven [6] techniques.…”

“…In terms of the modeling techniques, these papers develop and apply a variety of methods such as mesh-based Eulerian [1][2][3], meshfree Lagrangian [4,5,7,8], and data-driven [6] techniques. These models are applied to study Water 2022, 14, 3985. https://doi.org/10.3390/w14243985 https://www.mdpi.com/journal/water different hydraulics problems, including curved channels [1,2,11], channel confluences [10], air-core vortices [5], and submerged granular slides [3]. The article by Wang et al [1] studies the turbulent flow pattern at a curved channel (with a 135-degree bend), under the influence of negatively buoyant jets, using a threedimensional (3D) FVM.…”

“…Two articles by Shaheed et al [10,11] review recent progress on numerical simulations of secondary flows in two common morphological features of river channels, i.e., confluences and bends. The structure of the main flow features identified by the past literature, particularly the secondary flows, is discussed.…”