In the present work numerical investigations of the two-phase flow field inside a Rotating Packed Bed (RPB) are performed with the use of Computational Fluid Dynamics (CFD). The RPB geometry will eventually be used for the production of nanoparticles of CaCO3 and 4MgCO3Mg(OH)24H2O. In the respect, the development of appropriate numerical models for the optimization of the overall process is significant and the use of CFD methods and the development of representative CFD models can be of prime interest. For this reason, a computational grid modelling of the rotating packed bed geometry was created in which two fluids, one in gas phase and one in liquid phase, are flowing in co-flow alignment. For the gas phase fluid, properties of air were applied, while for the liquid phase properties of water were used. The Realizable k-e turbulence model was used for the computations together with the volume of fluid (VOF) methodology in order to model the two-phase flow development and the gas-liquid interactions. The numerical analysis was performed using a steady flow assumption by applying a rotating frame of motion for the RPB geometry. The RPB geometry was modelled as an isotropic porous medium of predefined pressure loss formula taking into consideration the RPB core geometrical characteristics. The results from the computations provided a detailed view inside the RPB core revealing the various interactions between the gas and liquid phases in relation to the RPB operational conditions. The results of the computational study will provide appropriate information that will help in the development of simpler but accurate RPB computational models which will be able to provide rapid and reliable results regarding the two-phase flow field development and interaction inside the RPB core.