Comparison of dynamic behavior between hard-sphere andsoft-sphere simulation in gas-solid fluidized beds
In order to compare the difference between the hard-sphere method and soft-sphere method, the dynamic behavior in gas-solid fluidized beds was simulated by the hard-sphere method and soft-sphere method in which particle diameters were unequal. Particle average velocities with increasing time and particle trajectories were compared. At the same time, the dynamic behavior in fluidized beds and the distribution of particle average velocity were also studied when restitution coefficients were different. Simulation results indicated that restitution coefficients of the hard-sphere method and soft-sphere method had distinct influence on particle average velocities. The bubbling phenomena could be simulated by the hard-sphere method when restitution coefficients were smaller, while such phenomena could be simulated by the soft-sphere method when restitution coefficients were larger.The larger restitution coefficients, the larger the change of particle average velocities in the hard-sphere method, but the smaller the change of particle average velocities in the soft-sphere method. Moreover, the CPU time in the hard-sphere method was much larger than that of the soft-sphere method due to the different ways in dealing with the collisions and the different time steps of particle collisions.