Time-Resolved 3D Wake Reconstruction of a Circular Cylinder Undergoing Vortex-Induced Vibration Using 2D Measurements*

Due to the high costs associated with three-dimensional (3D) flow measurement techniques, there is a strong need for more accessible methods to obtain 3D flow fields using fewer measurements and more affordable devices. This study addresses this need by focusing on time-resolved 3D flow reconstruction in the wake of a circular cylinder undergoing vortex-induced vibration (VIV), using two-dimensional, three-component (2D-3C) velocity images. Snapshot optimization (SO) and averaging SO techniques, with defined threshold errors, are employed to use the 2D images and reconstruct a volumetric flow field. Experimental data is acquired using volumetric Particle Tracking Velocimetry (PTV) measurements, and the required 2D data for reconstruction is extracted. The reconstructed 3D flow is then compared with the original volumetric data. The study spans various Reynolds numbers within the VIV lock-in range. Results indicate that the averaging SO technique reconstructs the flow with high accuracy and minimal discontinuity along the spanwise direction, outperforming the SO method. Additionally, the time-resolved flow field obtained using the averaging SO method is further analyzed through Proper Orthogonal Decomposition (POD) technique.