In this study, a coupled computational fluid dynamics (CFD) and discrete element method (DEM) model was developed to analyze the fluid-particle and particle-particle interactions in a 3D liquid-solid fluidized bed (LSFB). Validation of the model was carried out using the Electrical Resistance Tomography (ERT) experimental method. ERT was employed to measure the bed-averaged particle volume fraction (BPVF) of 0.002 m glass beads fluidized with water for various particle numbers and flow rates. A response surface method (RSM) statistical model was developed to predict BPVF values of the LSFB system. CFD-DEM simulation results were used to quantify the influence of individual interaction forces and contact parameters (particle-scale phenomena) on the LSFB performance. This was done by i) comparing the simulation results obtained from three common drag models (i.e. Gidaspow, Syamlal-O'brien, and Schiller-Naumann drag models) and experimental measurements, ii) quantifying the effect of the inclusion of other interaction forces (i.e. pressure gradient, virtual mass, and Saffman lift forces), and iii) conducting the contact parameter calibration. It was found that the combination of the Gidaspow drag model with pressure gradient and virtual mass forces provided the least percentage error between simulation results and experiments. Contact parameters calibration showed that viscous dissipation, lubrication effects, and particle rotation damping effects must be accounted for in wet particle systems. The difference between simulations and experiments was 4.74%, following the drag model selection, inclusion of relevant interaction forces, and contact parameter calibration. (C) 2018 Elsevier B.V. All rights reserved.