| Gas-particle flows are widespreadly existed in energy, chemical industry, metallurgy and other fields. Grasp of the mechanism of gas-solid flows is important. With the development of computer technology, numerical simulation has become one of the most promising methods for studying gas-solid flows.Large eddy simulation, which combines the theories from both the direct numerical simulation and Reynolds average numerical simulation, has less demand for the spatial resolution and can be applied to the more complex flow of higher Reynold number in the existing computer conditions. On the other hands, it can give more information of fluctuations compared with RANS. Therefore, LES has a promising development in gas-particle flows.Transport equations of gas-solid flows are filtered by means of the volume fraction weighted average method. Based on the kinetic theory of granular flow and the two-fluid model, large eddy simulation is performed for two-dimensional gas-particle flow in a riser. The time-averaged particles concentration and velocity distributions are obtained and the core-annular structure of particles flow is shown. Simultaneously, the effect of model coefficient Cg is analyzed. The value of model coffecient is recommented to take as 0.1 from present simulations. Considering the excessive dissipation, the model is corrected by wall-function. The results are in more reasonable agreement with experimental data.The gradient sub-grid scale model is applied to simulate gas-solid flow in a riser. Considering the model gives a large energy dissipation in the center region, the gradient sub-grid scale model is not suitable to be used in the simulation of risers. With the correction of drag coefficient, it's easier to form cluster particles and the time-averaged gas velocities and particles velocities are increased.
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