LAUSR

Abstract The central blockage accidents of a rectangular channel with an aspect ratio of 16.67 (50 mm in width and 600 mm in length with 3 mm spacing) are investigated using Particle Image Velocimetry (PIV) and Proper Orthogonal Decomposition (POD). 30% and 70% blockage ratios (α) are chosen to simulate low and high blockage scenarios, respectively. The Reynolds number is calculated to be 3641 based on the channel hydraulic diameter and the inlet velocity. It is found that two counter-rotating vortices are formed in the wake after blocking and the vortex shedding is suppressed for α = 70%. Specially, POD modes expose the remarkable influence of obstructions on the variations of flow structures. And a further phase-averaged analysis convincingly demonstrated the generation and evolution of vortex.