Forced pitching oscillations of a finite wing at low reynolds number.

Aeroelastic flutter is a self-excited instability wherein structural oscillations are amplified by the energy extracted from the surrounding flow. In this study, we investigate forced pitching oscillations of a finite wing with a NACA 0015 cross-section and aspect ratio 2, using direct numerical simulations at Re=1000. The pitching frequency is systematically varied to emulate the natural flutter frequency, with reduced velocities ranging from 0 to 10. Energy transfer between the flow and the structure serves as a criterion to distinguish flutter from non-flutter regimes. To gain insight into the underlying mechanisms driving pitch flutter, we employ a moment partitioning framework to quantify the contribution of vortical structures. In non-fluttering cases, trailing-edge vortices generate stabilizing moments that counterbalance energy input and suppress flutter onset. In contrast, no such stabilizing structures are present in fluttering cases, leading to unbalanced (positive) energy transfer and growing oscillations. Dynamic mode decomposition is also used to capture the temporal evolution of coherent structures in the cross-stream plane. Finally, data-driven latent space modeling techniques are used to extract low-dimensional embeddings of these flows that govern the flow–structure interactions. These representations offer promising avenues for reduced-order modeling and real-time transient flutter prediction.