The aim of this report is to present a model of a rigid-rotor system based on computational fluid dynamics (CFD), which is applied on a vertical axis wind turbine (VAWT) research. Its originality results from the use of the average value of the variable rotational speed method taken in a periodic steady-state (PSS) of the VAWT rotor instead of the classical fixed rotational speed method. This approach was chosen in order to determine the mechanical and aerodynamic parameters of the wind turbine. The modeling method uses an implicit Euler iterative solution strategy, which resolves the coupling between fixed and moving rotor domains. The main methods that were adopted are based on the three-dimensional modeling of the interaction of the fluid flow with a rigid-rotor. The strategy consists of using the Reynolds averaged Navier Stokes (RANS) equations with the standard k- ϵ and SST k- ω models to solve the fluid flow problem. To perform the rigid-rotor motion in a fluid, the one degree of freedom (1-DOF) method was applied. In the present study, the steady-state and dynamic CFD simulations of the Savonius rotor are adopted to contribute to the validation elements of the VAWT models that are used. The dynamic study allows the investigation of the rotor behavior and the relation between velocity, pressure, and vorticity fields in and around the rotor blades. The flow fields generated by the rotation of the Savonius rotor were investigated in the half revolution period of the rotor angle θ from 0° to 180°. In this range of θ, the focus is on generating and dissipating vortices. Copyright © 2013 John Wiley & Sons, Ltd.