In this article, 3D modeling and simulation of bubbling fluidized beds has been conducted using various drag models, and the model predictions were validated against reported experimental data and 2D simulation results. In this regard, different drag models reported in the literature including Gidaspow, Syamlal-O'Brien, Hill-Koch-Ladd, and Wen-Yu were applied. A standard o-Fluid Model (TFM) closed by the Kinetic Theory of Granular Flows (KTGF) was used to simulate bubbling gas-solid fluidized beds. Excellent agreements between the simulation results and experimental data, concerning bed expansion ratio, gas volume fraction, and time-averaged particles velocity, were found over a wide range of particle size, static bed height, and fluidization velocity. Moreover, comparison of 2D and 3D simulation results with experimental data shows that overpredictions attributed to 2D simulations can be a direct result of neglecting frictional stresses. In addition, it was found that the Wen-Yu drag model can provide better predictions for the bed expansion ratio and solids velocity relative to other drag models. (C) 2015 The Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.