Time-resolved Particle Image Velocimetry and structural analysis on a hemisphere-cylinder at low Reynolds numbers and large angle of incidence

摘要

Time-resolved planar Particle Image Velocimetry (PIV) experiments have been carried out in a water tunnel over a hemisphere-cylinder body at Reynolds number 1000, 2000 and 3000 and angle of incidence of 20. Proper Orthogonal Decomposition (POD) and Dynamic Mode Decomposition (DMD) analysis have been performed over such experimental data in order to identify flow patterns and provide a quantitative description of fluid motion and behavior. Results are in good agreement with Power Spectral Density (PSD) predictions. Three dominant DMD modes reproducing three-dimensional separation bubble and shear layer instabilities were detected and compared with POD results.