The decarbonization of the shipping industry has driven significant research efforts to reduce emissions. Among the proposed measures, wind-assisted propulsion has emerged as a viable solution. Flettner Rotors (FRs), i.e. rotating cylinders that generate thrust through the Magnus effect, are being investigated as part of this effort. In this context, the present study focuses on the development and validation of a CFD model for the long-term investigation of wind-assisted propulsion using FRs. The model, implemented in commercial software, is employed to simulate the turbulent flow around a two-dimensional rotating cylinder. Three different approaches for modeling cylinder rotation are implemented and evaluated: Moving Wall (MW), Sliding Mesh (SM) and Moving Reference Frame (MRF), in conjunction with two eddy-viscosity turbulence models, k-ω/SST (SST) and Spalart-Allmaras (SA), along with their Detached Eddy Simulation (DES) variants. The CFD model setup is described, and its validation is presented against both experimental data and high-fidelity three-dimensional Large Eddy Simulation (LES) data from the literature. The findings indicate that drag prediction is more challenging than lift prediction. The SST and SA models yield similar results, while the SM approach outperforms MW. Additionally, the MRF approach provides satisfactory results compared to SM but at significantly lower computational cost. Finally, the offline generation of a numerical database of aerodynamic coefficients for various Reynolds numbers and spin ratios using MRF is demonstrated.