Hydraulic Features of Flow through Local Non-Submerged Rigid Vegetation in the Y-Shaped Confluence Channel

Tong, Xuneng; Liu, Xiaodong; Yang, Ting; Hua, Zulin; Wang, Zian; Liu, Jingjing; Li, Ruoshui

doi:10.3390/w11010146

Cited by 15 publications

(15 citation statements)

References 42 publications

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“…Liu and Shan [22] used an analytical model to predict longitudinal profile of depth averaged streamwise velocity for simulated emergent cylindrical vegetation and used an experimental setup to validate the proposed model for short and long arrays of vegetation. Tong et al [23] investigated the effect of emergent rigid vegetation in a y shaped confluence channel and concluded that non submerged vegetation is responsible for changing the flow structure. Due to the vegetation, middle of the non-vegetated area in the vicinity of tributaries showed existence of high velocity region, and the disappearance of the secondary flow.…”

Section: Vertical Structurementioning

confidence: 99%

A Review on Hydrodynamics of Free Surface Flows in Emergent Vegetated Channels

Maji

Hanmaiahgari

Balachandar

et al. 2020

Water

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This review paper addresses the structure of the mean flow and key turbulence quantities in free-surface flows with emergent vegetation. Emergent vegetation in open channel flow affects turbulence, flow patterns, flow resistance, sediment transport, and morphological changes. The last 15 years have witnessed significant advances in field, laboratory, and numerical investigations of turbulent flows within reaches of different types of emergent vegetation, such as rigid stems, flexible stems, with foliage or without foliage, and combinations of these. The influence of stem diameter, volume fraction, frontal area of stems, staggered and non-staggered arrangements of stems, and arrangement of stems in patches on mean flow and turbulence has been quantified in different research contexts using different instrumentation and numerical strategies. In this paper, a summary of key findings on emergent vegetation flows is offered, with particular emphasis on: (1) vertical structure of flow field, (2) velocity distribution, 2nd order moments, and distribution of turbulent kinetic energy (TKE) in horizontal plane, (3) horizontal structures which includes wake and shear flows and, (4) drag effect of emergent vegetation on the flow. It can be concluded that the drag coefficient of an emergent vegetation patch is proportional to the solid volume fraction and average drag of an individual vegetation stem is a linear function of the stem Reynolds number. The distribution of TKE in a horizontal plane demonstrates that the production of TKE is mostly associated with vortex shedding from individual stems. Production and dissipation of TKE are not in equilibrium, resulting in strong fluxes of TKE directed outward the near wake of each stem. In addition to Kelvin–Helmholtz and von Kármán vortices, the ejections and sweeps have profound influence on sediment dynamics in the emergent vegetated flows.

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Section: Vertical Structurementioning

confidence: 99%

A Review on Hydrodynamics of Free Surface Flows in Emergent Vegetated Channels

Maji

Hanmaiahgari

Balachandar

et al. 2020

Water

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“…Yet, the shear layer dynamics may be influenced by the presence of vegetation because plants may affect the internal flow structure at a confluence especially in the secondary flow structure (Tong et al, 2019). As a result, our analysis shows that the vegetation may be the key driver of the junction hydrodynamics, with respect to other hydraulic and morphological features (e.g., discharge ratio, junction angle).…”

Section: River Confluences Morphodynamics In Presence Of Riparian Vegetationmentioning

confidence: 79%

Effects of vegetation at a bar confluence on river hydrodynamics: The case study of the Arno River at Greve junction

Artini

Calvani

Francalanci

et al. 2021

River Research & Apps

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River bars often form at river confluences due to variation in flow discharges or in sediment transport capacity; once these bars are grown, they constitute favourable habitats for vegetation development. In this work, we analysed the effect of vegetation above confluence bars on the hydrodynamics of a river reach. The case study considered is the Arno River reach at the Greve junction, where confluence bars expanded towards the opposite bank. A two-dimensional hydraulic model was implemented through BASEMENT software varying the flow discharge. Three-dimensional topographic data were used to generate the calculation mesh. Dendrometric surveys were carried out to describe the current state of the vegetation. Seven different vegetative scenarios were considered for numerical simulations, depending on different vegetation management conditions. Such scenarios are characterised by various plant densities, diameters, heights and species (herbaceous, shrub and arboreal), and, accordingly, different formu-

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“…The flow patterns at confluences influence the contaminant transport and affect the bed morphology in river networks (Kilic & Aral, 2009). Many studies have been conducted to explore the hydrodynamic features in river confluences (Boyer et al, 2006; Liu et al, 2019; Qing‐Yuan et al, 2009; Tong et al, 2019). Taylor (1944) was the first to study the hydraulic characteristics in open‐channel confluences through flume experiments.…”

Section: Introductionmentioning

confidence: 99%

An experimental study of the hydrodynamics and contaminant transport in a Y‐shaped confluence with flexible submerged vegetation

Tong

Liu

Yang

et al. 2022

Hydrological Processes

Self Cite

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Vegetation greatly affects the flow characteristics and contaminant transport in river confluences. In this study, the flow characteristics and contaminant transport in the non‐vegetated/vegetated Y‐shaped confluence were explored systematically through a series of experiments. A total of 10 scenarios were designed to answer the three main research questions: what is the difference between the flow characteristics and contaminant transport in (1) asymmetrical and Y‐shaped confluences; (2) non‐vegetated/vegetated Y‐shaped confluences; (3) vegetated Y‐shaped confluences with different confluence ratios? The experimental results revealed that vegetation remarkably changes the internal flow structure in Y‐shaped confluences. Briefly, the velocity profile can be divided into three vertical layers within the vegetated system, but it remains nearly constant in the non‐vegetated channel. Vegetation changes the circulation location and reduces the intensity of the secondary current, weakening the strength of contaminant mixing. However, the turbulent kinetic energy within the vegetated system is larger than that in the non‐vegetated case, and it peaks at the top of the vegetation canopy. Under different confluence ratio cases, the overall fluctuation of the longitudinal dispersion coefficients along the cross‐sections in the mainstream was similar but increasing the confluence ratio causes the circulation to appear to advance and enhances its intensity. In addition, the vegetation density (200 item/m2) in this study render the manning roughness coefficient at 0.068, which is larger than that under lower vegetation density cases. The outcomes from this study are helpful for both environmental and river management applications.

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Hydraulic Features of Flow through Local Non-Submerged Rigid Vegetation in the Y-Shaped Confluence Channel

Cited by 15 publications

References 42 publications

A Review on Hydrodynamics of Free Surface Flows in Emergent Vegetated Channels

A Review on Hydrodynamics of Free Surface Flows in Emergent Vegetated Channels

Effects of vegetation at a bar confluence on river hydrodynamics: The case study of the Arno River at Greve junction

An experimental study of the hydrodynamics and contaminant transport in a Y‐shaped confluence with flexible submerged vegetation

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