POD analysis of wind velocity field in the wake region behind vibrating three-dimensional square prism

This paper presents a study on systematic structure of wind velocity field in the wake region behind vibrating three-dimensional square prism. Particle image velocimetry (PIV) system was used to visually understand the characteristics of the wake. Focused on the length between prism's leeward wall and identified wake stagnation point, averaged wind velocity field in the wake region was evaluated. The result showed that the length of the wake region was consistent with the across-wind response in the vortex-induced oscillation. Proper orthogonal decomposition (POD) analysis was applied in order to extract the main structure of the overall physical phenomenon from the measured wind velocity field. The obtained eigenvectors of the first and the second modes indicated the Kármán's-type structure of vortex shedding and the result of their reconstruction was able to highlight the dominant structure of prism–wake interaction in the vortex-induced oscillation.