Recent studies have shown that the expanded bed heights of bubbling fluidized beds obtained from direct numerical simulations (DNS) are higher than those obtained from CFD-DEM method. In this study, we show that the consideration of the effect of either granular temperature using the model proposed by Tang et al. (AIChE Journal, 2016, 62: 1958-1969) or solid concentration fluctuation on the interphase drag force can significantly improve the agreement with the DNS results. This study highlights the importance of the fluctuation of state variables on the accurate CFD simulation of gas fluidization. (C) 2017 Elsevier Ltd. All rights reserved.