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.

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 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.

Distribusi Kecepatan dan Konsentrasi Sedimen Suspensi pada Aliran Menikung (Studi Kasus pada Saluran Irigasi Mataram Yogyakarta)

2016 ◽  
Vol 12 (1) ◽  
pp. 11
Author(s):  
Chairul Muharis
Keyword(s):  
Velocity Distribution ◽  
Flow Velocity ◽  
Suspended Sediment ◽  
Centrifugal Force ◽  
Suspended Sediment Concentration ◽  
Sediment Concentration ◽  
Low Velocity ◽  
Distribution Profile ◽  
Bend Flow ◽  
Distribution Of Flow

The flow velocity and suspended sediment concentration are important parameters of sediment transport mechanisms, especially for agradation and degradation problems. The centrifugal force at the bend channels will increased flow velocity at the outer bank of the bend. It is of course also affects the distribution of flow velocity toward the outside and the inside of the bend channels. The change of the velocity distribution  it is very possible also changes the distribution of suspended sediment concentration. In this paper will discuss the velocity distribution profile and distribution of sediment concentration in the bend flow. This research was conducted at Mataram Irrigation Channel Yogyakarta. The channel rectangular in shape and made of masonry with angle bend 580. Measuring the flow velocity used Propeller currentmeter and  sediment concentration used Opcon Probe. Measuring flow velocity and sediment concentration conducted simultaneously for each measurement point.The results showed that due to the centrifugal force in bend flow, flow velocity distribution and sediment concentration distribution undergoing significant change the outside and the inside of the bend. In general, the distribution of flow velocity toward the outerbank of the bend has increased and the distribution suspended  sediment concentration has decrease  and the opposite occurs innerbank of the bend. A low velocity on the inner bank of the channel bend causes larger grains of sediment that settles and potentially silting.

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