Secondary Flow in Curved Open Channels

Falcon, Marco

doi:10.1146/annurev.fl.16.010184.001143

Cited by 25 publications

(11 citation statements)

References 3 publications

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“…In addition, bathymetric complexities, such as braiding or curvature, may contribute to cross‐estuary circulation and lateral density gradients, leading to an along‐estuary front (Giddings et al, ; Falcon, ; Kalkwijk & Booij, ). Strong fronts appear on a high flood tide in the Snohomish River Estuary in Washington, USA, and the curvature and specific bathymetry are responsible for the frontogenesis.…”

Section: Introductionmentioning

confidence: 99%

Channel‐Trapped Convergence and Divergence of Lateral Velocity in the Pearl River Estuary: Influence of Along‐Estuary Variations of Channel Depth and Width

2020

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A cruise survey was conducted in the Pearl River Estuary (PRE) in May 2014. In situ observations during this cruise reveal that at the surface in the central channel of the PRE there was a strong convergence of lateral velocity during an ebb tide and a divergence during a flood tide. The ebb tide convergence was also observed in satellite synthetic aperture radar imagery. The Finite-Volume Coastal Ocean Model was executed in the PRE domain to accurately simulate the convergence and divergence of the cross-estuary velocity during ebb and flood tides, respectively. Numerical experiments in an idealized estuary domain are implemented with three distinct forcing scenarios: tide, river discharge, and a combination of both. Model results show that the cross-estuary momentum balance plays a significant role in the dynamics of the velocity convergence and divergence in the PRE. Additionally, the interaction between tide and river discharge enhances the surface convergence on ebb tide and generates the surface divergence on flood tide. The model results reveal that the along-estuary variation of channel depth and width is responsible for the tide-induced lateral velocity convergence and divergence in the channel, supported by the fact that when the channel depth and width are set to constant values in the model, the channel-trapped ebb convergence substantially weakens, and the flood divergence disappears. This study provides an indication for other wide estuaries.

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Section: Introductionmentioning

confidence: 99%

Channel‐Trapped Convergence and Divergence of Lateral Velocity in the Pearl River Estuary: Influence of Along‐Estuary Variations of Channel Depth and Width

2020

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“…Various simplified balances driving transverse circulation have been examined in detail. In an unstratified flow, channel curvature (or rotation) can drive secondary circulation with flow towards the outer bank at the surface and towards the inner bank at depth (Falcon 1984;Kalkwijk and Booij 1986). Stratification can establish lateral baroclinic pressure gradients that can in turn induce transverse circulation that can either enhance (e.g., Geyer 1993) or reduce (e.g., Chant and Wilson 1997) transverse flows.…”

Section: Introductionmentioning

confidence: 99%

Frontogenesis and Frontal Progression of a Trapping-Generated Estuarine Convergence Front and Its Influence on Mixing and Stratification

Giddings

Fong

Monismith

et al. 2011

Estuaries and Coasts

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Estuarine fronts are well known to influence transport of waterborne constituents such as phytoplankton and sediment, yet due to their ephemeral nature, capturing the physical driving mechanisms and their influence on stratification and mixing is difficult. We investigate a repetitive estuarine frontal feature in the Snohomish River Estuary that results from complex bathymetric shoal/ channel interactions. In particular, we highlight a trapping mechanism by which mid-density water trapped over intertidal mudflats converges with dense water in the main channel forming a sharp front. The frontal density interface is maintained via convergent transverse circulation driven by the competition of lateral baroclinic and centrifugal forcing. The frontal presence and propagation give rise to spatial and temporal variations in stratification and vertical mixing. Importantly, this front leads to enhanced stratification and suppressed vertical mixing at the end of the large flood tide, in contrast to what is found in many estuarine systems. The observed mechanism fits within the broader context of frontogenesis mechanisms in which varying bathymetry drives lateral convergence and baroclinic forcing. We expect similar trapping-generated fronts may occur in a wide variety of estuaries with shoal/channel morphology and/or braided channels and will similarly influence stratification, mixing, and transport.

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“…Figure 8b shows that secondary velocities on this section are developed in the right side due to the shear layer (abrupt change on the direction of velocities) between the junction of the two flows. Figure 8c shows that a secondary flow was only present on the right side of the section, and there was an over-elevation of water's surface due to the radial pressure force , known as the cross slope in the curve phenomenon (Falcón, 1984).…”

Section: Confluencementioning

confidence: 99%

Secondary currents: Measurement and analysis

Priego-Hernandez

Rivera-Trejo

2016

ATM

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RESUMENque describen la distribución de velocidades. Algunos fenómenos naturales que presentan estas funciones son los huracanes, los cuales son generados por las diferencias de presión; los ciclones, cuya fuente primaria de energía es el gradiente horizontal de temperatura, y los remolinos, que están ligados al gradiente de presión hidrostático. En el caso particular de los remolinos, éstos generan velocidades secundarias, las cuales son fenómeno también se observa en tornados, donde la fuerza centrífuga es mayor en la parte superior y luego va disminuyendo hacia el fondo, mientras que en los ríos se detecta particularmente en curvas y uniones -terización es fundamental. El objetivo de este estudio fue estimar las velocidades secundarias en la unión de dos ríos, a partir de mediciones de campo realizadas con medidores acústicos Doppler. Un segundo objetivo lo que su entendimiento ayudará a pronosticar cambios morfológicos en los ríos. ABSTRACTFluid dynamics has the purpose of understanding the movement of liquids and gases by functions that describe the distribution of velocities. Some natural phenomena that present these functions are hurricanes, generated by pressure differences; cyclones, developed by the horizontal temperature gradient; and eddies, associated with a hydrostatic pressure gradient. In the particular case of eddies, they generate addition, this phenomenon is observed in tornados, where the centrifugal force is greater in the upper layer and decreases towards the bottom, whereas the pressure gradient moves from a high to a low pressure; while in rivers it is detected particularly in bends or joins. Understanding the development of secondary hence their characterization is fundamental. The objective of this study was to obtain the secondary velocities developed as an effect of the union of two water currents, based on data acquired from Doppler Atmósfera 29 (1), 23-34 (2016(1), 23-34 ( ) doi: 10.20937/ATM.2016 © 2016 Universidad Nacional Autónoma de México, Centro de Ciencias de la Atmósfera. This is an open access article under the CC BY-NC-ND License (http://creativecommons.org/licenses/by-nc-nd/4.0/). 24 G. A. Priego-Hernández and F. Rivera-Trejo effect, a kind of results that are difficult to obtain in any other way. The flow mechanisms are related with erosion and sedimentation processes; therefore, understanding them might help to evaluate and predict morphological changes in rivers.

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Secondary Flow in Curved Open Channels

Cited by 25 publications

References 3 publications

Channel‐Trapped Convergence and Divergence of Lateral Velocity in the Pearl River Estuary: Influence of Along‐Estuary Variations of Channel Depth and Width

Channel‐Trapped Convergence and Divergence of Lateral Velocity in the Pearl River Estuary: Influence of Along‐Estuary Variations of Channel Depth and Width

Frontogenesis and Frontal Progression of a Trapping-Generated Estuarine Convergence Front and Its Influence on Mixing and Stratification

Secondary currents: Measurement and analysis

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