THE CONVECTION-DISPERSION EQUATION AND THE MECHANISM OF SUSPENSION IN TURBULENT OPEN-CHANNELS

Zhang Lei; Zhong Deyu; Wu Baosheng; Liu Lei

doi:10.6052/0459-1879-12-146

Volume 45 Issue 1

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Chinese Journal of Theoretical and Applied Mechanics > 2013 > 45(1): 83-93. > DOI: 10.6052/0459-1879-12-146 CSTR: 32045.14.0459-1879-12-146

Zhang Lei, Zhong Deyu, Wu Baosheng, Liu Lei. THE CONVECTION-DISPERSION EQUATION AND THE MECHANISM OF SUSPENSION IN TURBULENT OPEN-CHANNELS[J]. Chinese Journal of Theoretical and Applied Mechanics, 2013, 45(1): 83-93. DOI: 10.6052/0459-1879-12-146

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THE CONVECTION-DISPERSION EQUATION AND THE MECHANISM OF SUSPENSION IN TURBULENT OPEN-CHANNELS

State Key Laboratory of Hydroscience and Engineering, Tsinghua University, Beijing 100084, China

Funds: The project was supported by the National Natural Science Foundation of China (51039004) and the National Key Technologies R&D Program of China during the 12th Five-Year Plan Period (2012BAB05B01).

Received Date: May 17, 2012
Revised Date: October 21, 2012

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The suspended sediment usually occupies a large portion of the total load transported by streams in large fluvial rivers. Therefore, it is of crucial importance to study the mechanism involved in the suspension of suspended sediment. In this paper, we derive an equation for suspended sediment transportation and the sediment diffusion coeffcient based on the two-fluid model by introducing the concept of dispersion velocity, and apply the theory to calculate the concentration profiles of uniform two-dimensional open channel flows. Comparisons with the experimental data from Einstein and Chien and classical diffusion models are also presented, which show that present theory agrees well with the experimental data. In addition, we analyze the variations of influences of different effects contributing to the suspended sediment in the vertical direction. It is found that the suspension of the sediment in open channels is the result of three different actions, which are the turbulence diffusion of mixture, particle turbulence, and particle collisional stress. The result also shows that it is insu cient to ascribe the sediment in suspension solely to the turbulence of the flow.
- sediment,
- suspension,
- dispersion,
- diffusion,
- turbulence,
- two fluid model

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