Sediment diffusion coefficient model for predicting the vertical distribution of suspended sediment concentration in uniform open-channel flows

2020 ◽  
Vol 13 (21) ◽  
Author(s):  
Abdelali Terfous ◽  
Mira Sabat ◽  
Abdellah Ghenaim
Keyword(s):  
Diffusion Coefficient ◽  
Vertical Distribution ◽  
Suspended Sediment ◽  
Open Channel ◽  
Suspended Sediment Concentration ◽  
Sediment Concentration ◽  
Channel Flows ◽  
Open Channel Flows ◽  
Sediment Diffusion Coefficient ◽  
The Vertical Distribution

scholarly journals Fractal derivative model for the transport of the suspended sediment in unsteady flows

2018 ◽  
Vol 22 (Suppl. 1) ◽  
pp. 109-115 ◽  
Author(s):  
Shiqian Nie ◽  
Hong Sun ◽  
Xiaoting Liu ◽  
Wang Ze ◽  
Mingzhao Xie
Keyword(s):  
Vertical Distribution ◽  
Unsteady Flow ◽  
Suspended Sediment ◽  
Suspended Sediment Concentration ◽  
Spatial Location ◽  
Sediment Concentration ◽  
Equation Model ◽  
Advection Dispersion ◽  
Fractal Derivative ◽  
The Vertical Distribution

This paper makes an attempt to develop a Hausdorff fractal derivative model for describing the vertical distribution of suspended sediment in unsteady flow. The index of Hausdorff fractal derivative depends on the spatial location and the temporal moment in sediment transport. We also derive the approximate solution of the Hausdorff fractal derivative advection-dispersion equation model for the suspended sediment concentration distribution, to simulate the dynamics procedure of suspended concentration. Numerical simulation results verify that the Hausdorff fractal derivative model provides a good agreement with the experimental data, which implies that the Hausdorff fractal derivative model can serve as a candidate to describe the vertical distribution of suspended sediment concentration in unsteady flow.

scholarly journals Theoretical Model of Suspended Sediment Concentration in a Flow with Submerged Vegetation

Water ◽  
2018 ◽  
Vol 10 (11) ◽  
pp. 1656 ◽  
Author(s):  
Da Li ◽  
Zhonghua Yang ◽  
Zhaohua Sun ◽  
Wenxin Huai ◽  
Jianhua Liu
Keyword(s):  
Vertical Distribution ◽  
Suspended Sediment ◽  
Schmidt Number ◽  
Suspended Sediment Concentration ◽  
Sediment Concentration ◽  
Submerged Vegetation ◽  
Distribution Profile ◽  
Turbulent Schmidt Number ◽  
Rouse Number ◽  
The Vertical Distribution

Vegetation in natural river interacts with river flow and sediment transport. This paper proposes a two-layer theoretical model based on diffusion theory for predicting the vertical distribution of suspended sediment concentration in a flow with submerged vegetation. The suspended sediment concentration distribution formula is derived based on the sediment and momentum diffusion coefficients through the inverse of turbulent Schmidt number ( S c t ) or the parameter η which is defined by the ratio of sediment diffusion coefficient to momentum diffusion coefficient. The predicted profile of suspended sediment concentration moderately agrees with the experimental data. Sensitivity analyses are performed to elucidate how the vertical distribution profile responds to different canopy densities, hydraulic conditions and turbulent Schmidt number. Dense vegetation renders the vertical distribution profile uneven and captures sediment particles into the vegetation layer. For a given canopy density, the vertical distribution profile is affected by the Rouse number, which determines the uniformity of the sediment on the vertical line. A high Rouse number corresponds to an uneven vertical distribution profile.

Calculation Method about Vertical Distribution of Saturated Sediment Concentration Based on Exchange Equilibrium

2013 ◽  
Vol 405-408 ◽  
pp. 2287-2291
Author(s):  
Xiao Xiang Feng ◽  
Pei Jiu Yue
Keyword(s):  
Diffusion Coefficient ◽  
Vertical Distribution ◽  
Diffusion Theory ◽  
Sediment Concentration ◽  
Exchange Equilibrium ◽  
Sediment Diffusion Coefficient ◽  
The Difference ◽  
The Vertical Distribution ◽  
And Diffusion ◽  
Key Parameter

Diffusion theory is the leading one which is used to study the vertical distribution of sediment concentration. And diffusion coefficient is a key parameter to determine the vertical distribution of suspended sediment. First of all, the calculation methods are introduced based on the momentum transfer theory and fluctuating velocity. According to the sediment equation of exchange equilibrium in vertical, the new expression is obtained for sediment diffusion coefficient and the vertical distribution of sediment concentration. By the flume experimental data and field data in natural river, the difference is analyzed among the different expressions.

scholarly journals Vertical Distribution of Suspended Sediment under Steady Flow: Existing Theories and Fractional Derivative Model

2017 ◽  
Vol 2017 ◽  
pp. 1-11 ◽  
Author(s):  
Shiqian Nie ◽  
HongGuang Sun ◽  
Yong Zhang ◽  
Dong Chen ◽  
Wen Chen ◽  
...  
Keyword(s):  
Vertical Distribution ◽  
Turbulent Flow ◽  
Fractional Derivative ◽  
Suspended Sediment ◽  
Suspended Sediment Concentration ◽  
Sediment Concentration ◽  
Advection Diffusion Equation ◽  
The Vertical Distribution ◽  
Sediment Settling ◽  
Derivative Order

The fractional advection-diffusion equation (fADE) model is a new approach to describe the vertical distribution of suspended sediment concentration in steady turbulent flow. However, the advantages and parameter definition of the fADE model in describing the sediment suspension distribution are still unclear. To address this knowledge gap, this study first reviews seven models, including the fADE model, for the vertical distribution of suspended sediment concentration in steady turbulent flow. The fADE model, among others, describes both Fickian and non-Fickian diffusive characteristics of suspended sediment, while the other six models assume that the vertical diffusion of suspended sediment follows Fick’s first law. Second, this study explores the sensitivity of the fractional index of the fADE model to the variation of particle sizes and sediment settling velocities, based on experimental data collected from the literatures. Finally, empirical formulas are developed to relate the fractional derivative order to particle size and sediment settling velocity. These formulas offer river engineers a substitutive way to estimate the fractional derivative order in the fADE model.

On the Suspended Sediment Concentration Profile

2012 ◽  
Vol 212-213 ◽  
pp. 20-24 ◽  
Author(s):  
Chen Cheng ◽  
Zhi Yao Song ◽  
Yi Gang Wang ◽  
Jin Shan Zhang
Keyword(s):  
Boundary Condition ◽  
Suspended Sediment ◽  
Suspended Sediment Concentration ◽  
Order Approximation ◽  
Sediment Concentration ◽  
Suspended Sediment Transport ◽  
Surface Boundary ◽  
Sediment Diffusion Coefficient ◽  
Surface Boundary Condition ◽  
First Order Approximation

After analyzing the surface-boundary condition of suspended sediment concentration (SSC), Cheng et al.[7] further improved the sediment diffusion coefficient which was proposed by Bose and Dey[6]. Then an improved Rouse law (IRL) was developed. This equation, which has a similar form as Rouse law, not only overcomes the zero concentration at the free surface, but also behaves generally better than Rouse law and van Rijn equation over the whole water depth in the verification analysis. In this paper, the surface-boundary condition of SSC is further analyzed. It is elucidated that IRL satisfies the surface-boundary condition more reasonably than Rouse law. In addition, a first-order approximation of IRL is developed. From this approximation, we can easily get the explicit expression of the depth-averaged SSC without any implicit integrals to be solved numerically or by the help of a chart. This is very useful in the further study of non-equilibrium suspended sediment transport (SST).

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