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.

scholarly journals Flow Characteristics in a Gradually Expanded Rectangular Open Channel Flow

1992 ◽  
Vol 36 ◽  
pp. 379-384
Author(s):  
Masaru URA ◽  
Juichiro AKIYAMA ◽  
Junichiro KAWASAKI ◽  
Kouki ONITSUKA
Keyword(s):  
Channel Flow ◽  
Open Channel ◽  
Flow Characteristics ◽  
Open Channel Flow

scholarly journals FLOW CHARACTERISTICS OF GRADUALLY SHALLOWED OPEN CHANNEL FLOW

1998 ◽  
Vol 42 ◽  
pp. 871-876
Author(s):  
Masaru URA ◽  
Tomokazu OKAMOTO ◽  
Juichiro AKIYAMA ◽  
Kouki ONITSUKA ◽  
Norimitsu TAKEMOTO
Keyword(s):  
Channel Flow ◽  
Open Channel ◽  
Flow Characteristics ◽  
Open Channel Flow

scholarly journals A Study on the Friction Factor and Reynolds Number Relationship for Flow in Smooth and Rough Channels

Water ◽  
2021 ◽  
Vol 13 (12) ◽  
pp. 1714
Author(s):  
Yeon-Moon Choo ◽  
Jong-Gu Kim ◽  
Sang-Ho Park
Keyword(s):  
Friction Coefficient ◽  
Channel Flow ◽  
Open Channel ◽  
Flow Characteristics ◽  
Open Channel Flow ◽  
Shear Velocity ◽  
Estimation Methods ◽  
Flow Conditions ◽  
Key Factors ◽  
Mean Velocity

The shear velocity and friction coefficient for representing the resistance of flow are key factors to determine the flow characteristics of the open-channel flow. Various studies have been conducted in the open-channel flow, but many controversies remain over the form of equation and estimation methods. This is because the equations developed based on theory have not fully interpreted the friction characteristics in an open-channel flow. In this paper, a friction coefficient equation is proposed by using the entropy concept. The proposed equation is determined under the rectangular, the trapezoid, the parabolic round-bottomed triangle, and the parabolic-bottomed triangle open-channel flow conditions. To evaluate the proposed equation, the estimated results are compared with measured data in both the smooth and rough flow conditions. The evaluation results showed that R (correlation coefficient) is found to be above 0.96 in most cases, and the discrepancy ratio analysis results are very close to zero. The advantage of the developed equation is that the energy slope terms are not included, because the determination of the exact value is the most difficult in the open-channel flow. The developed equation uses only the mean velocity and entropy M to estimate the friction loss coefficient, which can be used for maximizing the design efficiency.

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