scholarly journals Impact of Different Vegetation Zones on the Velocity and Discharge of Open-Channel Flow

2021 ◽  
Author(s):  
Xiaonan Tang ◽  
Yutong Guan ◽  
Yuxiang Hu
Keyword(s):  
Shear Layer ◽  
Management Practices ◽  
Open Channel ◽  
Flow Characteristics ◽  
Flow Region ◽  
Free Flow ◽  
Flow Process ◽  
Riparian Management ◽  
Free Zone ◽  
Rigid Vegetation

Different types of vegetation widely exist in rivers and wetlands. The vegetation will affect the ecological environment and flow process, thus becoming increasingly significant in river engineering and aquatic environmental management. Previous research on vegetated flow is mainly to understand the flow structure of open channels with fully covered one-layer vegetation. However, vegetation often grows along a river bank and co-exists in different heights. The present paper presents experimental results about the flow characteristics of an open-channel with two sides covered by differently layered vegetation, focusing on the effect of vegetation on the velocity distribution and discharge. Two heights of dowels in 10 cm and 20 cm were used to simulate rigid vegetation and arranged in a linear form on both sides of a channel bed under emergent and fully submerged flow conditions. The velocity at different positions was obtained using ADV (Acoustic Doppler Velocimetry). Measured results demonstrate that there exists a shear layer between free-flow and vegetated zones, indicating that the flow transition occurs between fast-moving flow in the free zone and slowly obstructed flow in the vegetated zone and induces a high shear layer and transverse coherent vortices near the interface. Furthermore, compared with the emergent condition, the discharge through the free-flow region slightly decreases under full submerged conditions while the discharge in the vegetated region increases, indicating that the vegetation does not significantly change the discharge percentage in the free region. These findings on differently-layered vegetation would help riparian management practices to maintain healthy ecological and habitat zones.

Flow characteristics in open channels with aquatic rigid vegetation

2020 ◽  
Vol 32 (6) ◽  
pp. 1100-1108
Author(s):  
Yan-jie Wu ◽  
He-fang Jing ◽  
Chun-guang Li ◽  
Ying-ting Song
Keyword(s):  
Flow Characteristics ◽  
Open Channels ◽  
Rigid Vegetation

scholarly journals Interactions between Tandem Cylinders in an Open Channel: Impact on Mean and Turbulent Flow Characteristics

Water ◽  
2021 ◽  
Vol 13 (13) ◽  
pp. 1718
Author(s):  
Hasan Zobeyer ◽  
Abul B. M. Baki ◽  
Saika Nowshin Nowrin
Keyword(s):  
Turbulent Flow ◽  
Open Channel ◽  
Recirculation Zone ◽  
Three Dimensional ◽  
Flow Characteristics ◽  
Flow Recirculation ◽  
Tandem Cylinders ◽  
Flow Development ◽  
The Mean ◽  
Recirculation Length

The flow hydrodynamics around a single cylinder differ significantly from the flow fields around two cylinders in a tandem or side-by-side arrangement. In this study, the experimental results on the mean and turbulence characteristics of flow generated by a pair of cylinders placed in tandem in an open-channel flume are presented. An acoustic Doppler velocimeter (ADV) was used to measure the instantaneous three-dimensional velocity components. This study investigated the effect of cylinder spacing at 3D, 6D, and 9D (center to center) distances on the mean and turbulent flow profiles and the distribution of near-bed shear stress behind the tandem cylinders in the plane of symmetry, where D is the cylinder diameter. The results revealed that the downstream cylinder influenced the flow development between cylinders (i.e., midstream) with 3D, 6D, and 9D spacing. However, the downstream cylinder controlled the flow recirculation length midstream for the 3D distance and showed zero interruption in the 6D and 9D distances. The peak of the turbulent metrics generally occurred near the end of the recirculation zone in all scenarios.

scholarly journals Riparian forestry management and adult stream insects

2004 ◽  
Vol 8 (3) ◽  
pp. 545-549 ◽  
Author(s):  
R. A. Briers ◽  
J. H. R. Gee
Keyword(s):  
Riparian Vegetation ◽  
Management Practices ◽  
Food Sources ◽  
Tree Cover ◽  
Strong Impact ◽  
Riparian Management ◽  
Stream Insects ◽  
Larval Stages ◽  
Forestry Management ◽  
Coniferous Plantation

Abstract. The impacts of coniferous plantation forestry on the biology of upland streams in the UK are firmly established. Whilst benthic communities have been well studied, very little research has considered the impacts of riparian forestry management on adult stream insects, yet the essentially terrestrial adult (reproductive) phase may be important in determining the abundance and distribution of larval stages. Riparian vegetation has a potentially strong impact on survival and success of adult stages through alteration of microclimate, habitat structure and potential food sources, in addition to effects carried over from larval stages. Here, current riparian management strategies are analysed in the light of available information on the ecology of adult stream insects. On the whole, management practices appear to favour adult stream insects, although an increase in tree cover in riparian areas could be beneficial, by providing more favourable microclimatic conditions for adults. This conclusion is drawn based on rather limited information, and the need for further research into the effects of riparian forestry management on adult stream insects is highlighted. Keywords: microclimate, plantation, life history, riparian vegetation

scholarly journals Turbulent flow structure at a 90-degree open channel confluence: Accounting for the distortion of the shear layer

2016 ◽  
Vol 12 ◽  
pp. 130-147 ◽  
Author(s):  
Saiyu Yuan ◽  
Hongwu Tang ◽  
Yang Xiao ◽  
Xuehan Qiu ◽  
Huiming Zhang ◽  
...  
Keyword(s):  
Turbulent Flow ◽  
Shear Layer ◽  
Flow Structure ◽  
Open Channel ◽  
Turbulent Flow Structure ◽  
Channel Confluence

Transverse Distribution of the Streamwise Velocity for the Open-channel Flow With Floating Vegetated Islands

2021 ◽  
Author(s):  
Xuecheng Fu ◽  
Feifei Wang ◽  
Mengyang Liu ◽  
Wenxin Huai
Keyword(s):  
Channel Flow ◽  
Open Channel ◽  
Flow Characteristics ◽  
Open Channel Flow ◽  
Streamwise Velocity ◽  
Transport Efficiency ◽  
Transverse Distribution ◽  
Floating Vegetation ◽  
Shear Turbulence ◽  
Field Disturbance

Abstract Floating vegetation islands (FVIs) have been widely utilized in various river ecological restoration projects due to their ability to purify pollutants. FVIs float at the surface of shallow pools with their roots unanchored in the sediment. Biofilm formed by roots under islands filters nutrients and particles in the water flowing through it. Flow field disturbance will occur and transverse distribution of flow velocity will change due to the existence of FVIs. Transport efficiency of suspended solids, nutrients, and pollutants will also be altered. A modified analytical model that considers effects of boundary friction, drag force of vegetation, transverse shear turbulence, and secondary flow is established to predict transverse variation of depth-averaged streamwise velocity for the open-channel flow with FVIs using Shiono and Knight method. The simulation results with suitable boundary conditions successfully predicted lateral profile of the depth-averaged streamwise velocity compared with the experimental results of symmetrical and unsymmetrical arrangements of FVIs. Hence, the presented model can provide guidance for investigating flow characteristics of rivers with FVIs.

Study of flow characteristics within randomly distributed submerged rigid vegetation

2018 ◽  
Vol 31 (2) ◽  
pp. 358-367
Author(s):  
Paromita Chakraborty ◽  
Arindam Sarkar
Keyword(s):  
Flow Characteristics ◽  
Rigid Vegetation
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