Based on an Eulerian-Eulerian approach, a computational fluid dynamic (CFD) model for gas-solid system has been developed to investigate the hydrodynamics in fluidized beds. With this model, jet penetration height, jet frequency, time-averaged axial gas velocity profile, and time-averaged voidage profile have been simulated in a two-dimensional bed. The computational results indicate that the jet penetration height increases with increasing the jet gas velocity. The jet frequency decreases with increasing the jet gas velocity and decreasing particle diameter. The time-averaged axial gas velocity profile becomes 'lower' and 'wider' and the time-averaged voidage decreases with increasing distance from the jet nozzle. These conclusions appear in good agreement with the experimental and simulated data in the literature. Copyright (C) 2004 John Wiley Sons, Ltd.