Unsteady aerodynamics modelling and its application in aeroelastic stability analysis

An identification technique is used to construct reduced-order models (ROMs) for the incompressible flow past a circular cylinder at low Reynolds numbers. The proposed method is capable of constructing simple models for both the stable and unstable flows at the vicinity of critical Reynolds number. Linear ROMs are then validated in the time domain by comparing their harmonic forcing responses to that of full system in direct numerical simulations. Finally, the validity of linear ROMs is most clearly shown by using them for stability analysis of an elastically-mounted cylinder. The instability boundaries predicted by the linear dynamics model compare reasonably well to that of direct CFD/CSD simulations, while the computational cost can be reduced by nearly 2 orders of magnitude. Moreover, this kind of linear ROMs can also be utilized to feedback controller design and active flow control in further research.