Rapid progress of Computational Fluid Dynamics (CFD) allowed CFD to move past simple tasks and become a viable tool for the analysis of complex problems, such as turbo-machines. Nevertheless, due to the complexity of turbomachinery, some simplifications regarding interface and domain handling are sought in order to allow for reasonable simulation execution times. Most often, only a part of the whole turbomachine geometry is simulated, which decreases computational demands. To enable communication between domain regions wherein different rotation (or other movement) is modelled, between ill-connected or overlapping regions, or between cyclic patches bounding partial geometry domains, various interfaces are used. Moreover, steady-state ”frozen rotor” methods are frequently used to approximate transient problems but avoid computationally demanding transient simulations. This Thesis offers an overview of several rotor-stator interfaces available in foam-extend, with both theoretical background and numerical simulations. A series of numerical simulations is performed on a Contra-Rotating Propeller set (CRP), investigating different rotor-stator interface handling methods: • Steady-state simulations using the Multiple Reference Frame (MRF) approach and the whole CRP geometry with General Grid Interface (ggi). • Steady-state MRF simulations of a quarter CRP geometry using overlapGgi and cyclicGgi interfaces across periodic boundaries. Additional simulations are performed to investigate the effects of initial propeller position. • Quarter CRP geometry steady-state MRF simulations using cyclicGgi and mixingPlane interfaces. • Transient simulation of a quarter CRP geometry with the cyclicGgi and overlapGgi interfaces. The results were analysed in terms of hydrodynamic performance coefficients, showing good agreement between quarter and full CRP simulations and validating the interfaces used. Comparison to experimental data revealed good agreement with steady-state results for high-efficiency conditions and good agreement with transient simulations for lower-efficiency conditions.