Visualization of the Flow in the Wake of a Finite-Height Square Prism

Flow over a finite-height surface-mounted square prism of aspect ratio AR = 3 (AR = H/D where H is the height and D is the prism width) at a Reynolds number Re = 500 has been investigated using the Snapshot Proper Orthogonal Decomposition (POD) method. In particular, the instantaneous velocity fields in three horizontal spanwise planes at y/D = 1, 2 and 3 generated by Large Eddy Simulation (LES) have been studied to gain insight into the vortical structures in the prism wake. The study tracked the development of the prism wake over a single period using the most energetic POD modes. A scatter plot of the first two POD temporal coefficients successfully extracted the phase information of the flow field, and a reconstruction of the fluctuating velocity field using the first two POD modes was used to approximate the phase-averaged flow structures. Different POD modes can be associated with either anti-symmetric or symmetric vortex shedding characteristics of the wake.