Imaging of unsteady separated flows: global interpretation with particle image velocimetry

Quantitative characterization of unsteady, separated flows is central to understanding the physics of flow-structure interactions, which can give rise to vibration and noise generation. Global, instantaneous representations, obtained from high-image-density particle image velocimetry, can provide a basis for identification and classification of flow patterns. Moreover, these representations allow direct links to established theoretical concepts, which can be expressed in terms of vorticity. Case studies of vortex-dominated flows are addressed using these approaches, with the aim of defining challenges and future prospects.