Visualization and modal decomposition of vortex street behind circular cylinder

Time resolved particle image velocimetry measurement of vortex street behind circular cylinder was carried out. Vortex street was measured for Reynolds numbers up to few thousands. Obtained results were processed by visualizations of moving particles and by standard evaluation of vector fields from the set of images. Modal decomposition of measured flow field was done using propper orthogonal decomposition where the structure of energetically most important modes was identified for several Reynolds numbers. The values of Strouhal number was analyzed from temporal evolution of dominant modes obtained using proper orthogonal decomposition. Circular cylinder is placed in the test section between two panels made from transparent plexiglass. Transparent plexiglass was chosen because of the use of visualization techniques for the measurement of the flow field behind the cylinder.