The hydrodynamics flow of solid-liquid fluidized beds has been studied through the simulation by means of coupling Discrete Element Method (DEM) and Computational Fluid Dynamics (CFD). The coupling has been done through the drag force. The interaction forces between a fluid (liquid) and a granular medium (particles) is translated through a drag force. The effect of local particles concentration on the drag force is modeled by a porosity function f(epsilon)(m)=epsilon(-m.n). The value of exponent of porosity (m.n) shows substantial dependence on the size of the REV (Representative Volume Element). A validation of the method by comparison with experimental data is presented. It is proposed also as an illustration of three different geometries of fluidizing columns (column simple, column with interior plate and column with two lateral inlets). For each of them, simulation results are analyzed, through a fluidization indicator. These examples illustrate the ability of the coupling DEM-CFD method presented in this work to optimize complex granular flow. (C) 2016 Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.