Design and optimisation og various types of machinery has been significantly improved with the utilization of numerical simulations. Computational Fluid Dynamics (CFD) deals with numerical simulations of fluid flow in a wide variety of cases. One of the premier applications of CFD is simulating fluid flow inside turbomachines. Turbomachines play a vital role in energy conversion and as such it is important that turbomachines operate efficiently and flexibly. A key element that needs to be addressed when doing turbomachinery CFD simulations is the so called rotor-stator interface. The fluid flow inside a turbomachine is often assumed periodic which allows for only a part of the machine to be simulated thus, lowering the required computational resources. Computational resources can also be spared with approximating transient fluid flow with a quasi-steady state solution, the so called frozen rotor approach. In this thesis the fluid flow inside the IDAC is simulated using the open source CFD package OpenFOAM. The multi-stage axial turbo compressor was developed and extensively tested at RWTH Aachen University. In order to resolve the rotor-stator interaction two different types of interfaces are used: the mixing plane interface and the General Grid Interface (GGI). Since only a part of the compressor, a single passage is simulated a periodic boundary condition must be applied. For this purpose a variation of the GGI is employed. Numerical simulations are performed for four different operating points, two at the nominal design speed and two at 68% of the nominal design speed. The results of numerical simulations are presented as images of the flow field for different variables but also compared to avaliable experimental results in terms of mass flow rate, total pressure ratio, and efficiency.