In the present study, important features of the two-phase flow in a fluidized bed crystallizer are examined by numerical computations and companion experiments. The simulations are carried out using a coupled CFD-DEM approach (CFD: Computational Fluid Dynamics; DEM: Discrete Element Method). After validating an open-source CFD-DEM software tool for this purpose, regions within the crystallizer with unfavorable hydrodynamic features and thus a negatively impacted process outcome have been identified. This was first accomplished by single-phase CFD simulations. Then, the validated CFD-DEM model delivers valuable information that is difficult or even impossible to measure experimentally with sufficient accuracy, such as the velocity and position of fluidized crystals within the crystallizer. Since the simulations are computationally challenging, a compromise between simulated process time and number of simulated particles must be found. Hence, the CFD-DEM simulations are not utilized to simulate the whole crystallization process, but to examine a short time-window in detail. Corresponding findings confirm proper fluidization of the crystals support the model reduction carried out in a parallel project. (C) 2017 The Authors. Published by Elsevier Ltd.