A PIV study of the near wake flow features of a square cylinder: influence of corner radius

In this study, the near wake characteristics of transversely oscillating square-section cylinders with different corner radii were investigated using the particle image velocimetry (PIV) technique in a water channel with turbulence intensity of 6.5%. Five models with r/B = 0, 0.1, 0.2, 0.3, and 0.5, respectively (where r and B represent the corner radius and the characteristic dimension of the body, respectively), were studied, with the body oscillation limited to that under the lock-in condition. Corner radius was found to significantly influence the characteristics of the flow around the bodies, both under stationary and oscillating conditions. The results indicate that the Strouhal number and vortex strength of the flow increase and decrease, respectively, with an increase in the r/B ratio. The spacing between two rows of vortices (b) as well as that between consecutive vortices in a row (a) was also found to decrease with the increase in the corner radius. The b/a ratio was found to be nearly independent of the r/B ratio and body oscillation.