Computational Fluid Dynamics (CFD) using the Dynamic Fluid/Body Interaction (DFBI) model had been carried out to investigate the wind direction dependency of a 2D-rotor pair. Although the experiments showed the tendency of greater influence of the deflection of the wake in the CO (co-rotating) condition than the IR (inverse-rotating) condition, the CFD analysis showed the opposite tendency in the power distribution. There was no clear difference between the CO and IR conditions in regards to the power per unit area of the rotor pair.