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You are here : eLibrary : IAHR World Congress Proceedings : 35th IAHR Congress - Chengdu (2013) : THEME 2 - JOHN F. KENNEDY STUDENT PAPER COMPETITION : An Effective Euler-Lagrange Model for Sediment Transport in Open Channel Flows
An Effective Euler-Lagrange Model for Sediment Transport in Open Channel Flows
Author : Huabin Shi
An Euler-Lagrange two-phase flow model is developed for the simulation of sediment transport in open channel flows, with an eddy interaction model (EIM) coupled to describe the effect of fluid turbulence on the particle diffusion. For the continuous phase, the distributions of the mean fluid velocity and the turbulence kinetic energy with its dissipation rate are directly given by the well established empirical formulas. For the dispersed phase, all sediment particles are tracked with the Runge-Kutta method to obtain the particle trajectories and velocities. The EIM is employed to compute the velocity fluctuations of the fluid needed in the equation of motion, which govern the turbulent diffusion of particles. The fluctuating fluid velocity components at the particle position are randomly sampled as a Gaussian distribution with zero mean and turbulence intensity for the standard deviation. The Gaussian random number keeps unchanged in a finite eddy-particle interaction time defined as the minimum of the eddy lifetime and the eddy traversal time. At the end of the interaction time, the particle will be trapped by a new eddy and the fluctuating fluid velocity will be calculated with another Gaussian random number. The numerical model developed in this study is employed to compute the distribution of the lowly concentrated suspended load in open channel flows, and it is shown to perform very well for fine sediments. However, the computed nondimensional sediment concentrations by the numerical model are significantly smaller than the laboratory data for the medium-sized and the coarse cases, which shows that the numerical model underestimates the turbulent diffusion of the coarse sediment. A modified formula is thus proposed for the fluid turbulence enhancement surrounding a particle owing to the wake and the vortex shedding. The computational results of the modified numerical model coincide with the measured data in experiments of the coarse sediment. Besides, the nondimensional concentration profiles based on the Rouse formula are also used for comparison. It shows that the Euler-Lagrange model proposed in this study performs much better than the Rouse formula.
File Size : 311,162 bytes
File Type : Adobe Acrobat Document
Chapter : IAHR World Congress Proceedings
Category : 35th IAHR Congress - Chengdu (2013)
Article : THEME 2 - JOHN F. KENNEDY STUDENT PAPER COMPETITION
Date Published : 18/07/2016
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