The distance of the cylinder axis from the outlet of the contraction is around ten times the cylinder edge to ensure adequate decay of free stream disturbances (Sohankar et al. (1998)). The velocity profiles behind a square cylinder with and without endplates are compared at the midplane and at an offset location (z = 5) for three downstream locations (x = 2; 5 and 10) (see Figures 3.27 and 3.28). Results from two Reynolds number (Re=220 and 370) have been shown. The difference in the velocity profiles at different spanwise locations was found to be minimal for both configurations with and without end plates (except at x=10 and Re=370). At x=10 location, the effect of end plates is unclear. The low turbulence level in the test section along with thin boundary layers probably lead to a small wall effect. Hence no endplate has been used in the subsequent experiments. In the present study, the effect of cylinder oscillation on wake structure has also been reported. The use of end plates would have increased the experimental complexity required for the end plate arrangements.

Figure 3.28: Effect of endplate on mean velocity profiles behind a square cylinder for two spanwise locations, z=0 (center) and z=5 (oset) at x=2. Reynolds number = 220 and 370.