A comparison between snapshot POD analysis of PIV velocity and vorticity data

Abstract

Proper orthogonal decomposition (POD) was performed on both the fluctuating velocity and vorticity fields of a backward-facing step (BFS) flow at Reynolds numbers of 580 and 4,660. The data was obtained from particle image velocimetry (PIV) measurements. The vorticity decomposition captured the fluctuating enstrophy more efficiently than the equivalent velocity field decomposition for a given number of modes. Coherent structures in the flow are also more easily identifiable using vorticity-based POD. A common structure of the low-order vorticity POD modes suggests that a large-scale similarity, independent of the Reynolds number, may be present for the BFS flow. The POD modes obtained from a..