Open channel flow within and above a layered vegetation: Experiments and first-order closure modeling

Rahimi, Hamidreza; Tang, Xiaonan; Singh, Prateek Kumar; Li, M.; Alaghmand, Sina

doi:10.1016/j.advwatres.2020.103527

Cited by 17 publications

(5 citation statements)

References 34 publications

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“…Furthermore, the overall velocity profile in Zone 3.2 is much larger than that in Zone 3.1, which is significantly larger than that in the vegetation zone. This result shows that the vegetation decreases the flow velocity through the vegetation, which is not surprising because of the additional friction of vegetation to the flow, as observed by other researchers [6,21]. Furthermore, the vegetation influences the free zone's flow, revealing the smaller velocity in the zone close to the vegetation than that in the zone far from the vegetation.…”

Section: Experimental Flow Conditionssupporting

confidence: 83%

“…For understanding the flow structure of channels with mixing-layered vegetation, some experimental studies were done in an open channel fully covered with a coexistence of tall and short vegetation (e.g. [20][21][22][23]). Most recently, Tang et al [24][25][26] conducted some experimental studies on the flow characteristics of a channel with two-layered vegetation that covered part of the channel bed.…”

Section: Introductionmentioning

confidence: 99%

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Discharge and velocity variation of flows in open channels partially covered with different layered vegetation

et al. 2021

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The role of vegetation in the natural environment has drawn great interest recently. The vegetation can change the velocity distribution due to its additional resistance on the flow, consequently affecting the nutrient and pollutant transport, and the habitats. Due to the complexity of flow and vegetation interaction, many previous researchers have studied the flow structure of channels with uniform vegetation. Few studies have been done on the flow of open channels partially covered vegetation of different heights on one side of the channel, which commonly exists in natural rivers. Through novel experiments for such a vegetated flow, this paper shows the influence of different layered vegetation on the velocity profile and discharge, which indicates that the velocity in the vegetation zone is significantly smaller than that in the free-flow zone and that the velocity profiles in the short and tall vegetation zones are very different. The flow through the free-flow zone is dominant (about 75%) despite its half width, and its discharge percentage slightly decreases as increasing flow depth.

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Section: Experimental Flow Conditionssupporting

confidence: 83%

Section: Introductionmentioning

confidence: 99%

Discharge and velocity variation of flows in open channels partially covered with different layered vegetation

et al. 2021

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“…The distinct velocity profiles above z = h demonstrate the impact of the upstream vegetation. As Group A1 are behind the short after tall vegetation, which is like double-layered vegetation, the velocity profile in Group A1 reveals a typical velocity vertical distribution of double-layered vegetation flow, given by Rahimi et al (2020). The small variation of velocity in layers 2 and 3 of Group A1 is affected by the upstream tall vegetation due to its retarding and bocking effect.…”

Section: Lateral Variation Of Velocity Profiles Directly Behind Veget...mentioning

confidence: 96%

“…Limited experimental studies have been performed on the flow through a mixing array of short and tall vegetation, so-called double or two-layered vegetation (e.g. Tang et al, 2021b;Rahimi et al, 2020;Tang et al, 2019;Huai et al, 2014), showing significant different velocity profiles from the flow through one-layered vegetation. It is still poorly understood how multi-layered vegetation affects the flow.…”

Section: Introductionmentioning

confidence: 99%

Effect of Mixed Vegetation of Different Heights on Open Channel Flows

Tang¹,

Guan²,

Li³

et al. 2023

GEP

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Vegetation of different heights commonly grows in natural rivers, canals and wetlands and affects the biodiversity and morphological process. The role of vegetation has drawn great attention in river ecosystems and environmental management. Due to the complexity of the vegetated flow, most previous research focuses on the effect of uniformed one-layered vegetation on the flow structure and morphological process. However, less attention was paid to the impact of the mixing vegetation of different heights, which is more realistic and often occurs in natural riverine environments. This paper aims to investigate the effect of mixing three-layered vegetation on flow characteristics, particularly the velocity distribution, via a novel experiment. Experiments were performed in a titling water flume fully covered with vegetation of three heights (10, 15 and 20 cm) arranged in a staggered pattern, which is partially submerged. Velocities at different positions along a half cross-section were measured using a mini propeller velocimeter. Observed results showed that the velocity has a distinct profile directly behind vegetation and behind the vegetation gap. The overall profile has two distinct reflections about ¼ below or near the top of short vegetation (h): the velocity remains almost constant in the bottom layer (<0.75 h) and then fast increases until the top of short vegetation; after a gradual increase, the velocity rapidly increases to the water surface. Moreover, in the upper layer (z > h) the velocities directly behind the middle after short vegetation increase much faster than those directly behind the short after tall vegetation. The finding in this study would help river riparian and ecosystem management.

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“…In emergent conditions, the vertical distribution of longitudinal velocities in a uniform condition varies with depth [3,4]. In submerged conditions, the vertical distribution of longitudinal velocities is more complicated than for emergent conditions [5][6][7].…”

Section: Introductionmentioning

confidence: 99%

Numerical Modelling of Turbulence Kinetic Energy in Open Channel Flows with Mixed-Layer Vegetation

Rahimi,

Fael,

Taborda

et al. 2023

Water

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Vegetation plays a vital role in the flow characteristics of natural open channels, such as rivers. Typically, vegetation density is higher in the lower layer and sparser in the upper layer of these channels. In this research, Ansys Fluent and the k–ϵ model have been employed to simulate various vegetation configurations to capture intricate flow complexities within vegetation regions. Numerical analysis demonstrated that the numerical results align with anticipated Turbulence Kinetic Energy data obtained from analytical and experimental studies. Our findings revealed that double-layer vegetation induces a more intricate flow distribution. In the spaces between vegetation zones, Turbulence Kinetic Energy decreases due to the resistance imposed by the vegetation patches. This resistance has positive implications for sustaining aquatic life and facilitating sediment deposition, promoting a more environmentally sustainable outcome.

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Open channel flow within and above a layered vegetation: Experiments and first-order closure modeling

Cited by 17 publications

References 34 publications

Discharge and velocity variation of flows in open channels partially covered with different layered vegetation

Discharge and velocity variation of flows in open channels partially covered with different layered vegetation

Effect of Mixed Vegetation of Different Heights on Open Channel Flows

Numerical Modelling of Turbulence Kinetic Energy in Open Channel Flows with Mixed-Layer Vegetation

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