(448ab) Simulations of Flow Behavior of Particles in a Liquid-Solid Fluidized Bed Using a Second-Order Moments Model

The flow behavior of particles is simulated using the Eulerian-Eulerian two-fluid model approach with a second-order moments method for solids phase in the liquid-solid fluidized bed. Transport equations for the velocity moments and closure equations for the particle phase are used on the basis of the second-order moments method and the kinetic theory of granular model, respectively. The anisotropic characteristic of fluctuation is predicted based on second-order moments of particles. Simulated results are compared with the experimental data of Razzak et al. in a liquid-solid fluidized bed. Simulated results indicate that the axial second-order moments M_zz in the direction of flow are much larger than the radial second-order moments M_xx. The components of second-order moments in all direction are increased with increasing liquid velocity. The simulated granular temperature is increased, reaches a maximum, and then decreases with the increase of solid volume fraction. We also conduct the simulations to verify the numerical model for the downcomer, and the same conclusion as the riser is obtained from the two different models. Through comparison of various simulation models, it was found that the velocity fluctuation of particles is a key factor in influencing the hydrodynamics characteristics.