A novel approach to the control of vortex shedding downstream of a circular cylinder by control rod

This study investigates how the positioning of control rods affects the flow structure in the wake of a circular cylinder, focusing on the control of vortex shedding. This study elaborates the critical role of control rod positioning and diameter in optimizing flow control strategies to minimize wake disturbances around circular cylinders. Particle Image Velocimetry (PIV) measurements were conducted in a closed-loop water channel at a fixed Reynolds number of Re = 1.5 x 104, using control rods of varying diameters positioned at specific locations (namely C1, C2, and C3) relative to the approximate location of vortical interactions. The results demonstrate that the control rod placement significantly has altered the flow downstream of the circular cylinder, particularly for the C3 configuration with d/D = 0.29 in which Reynolds shear stress concentrations displace away from the cylinder and the vortex formation length extends. The turbulent kinetic energy (TKE) and vortex shedding frequency also have been reduced. Phase-averaged vorticity contours have revealed that control rods extend shear layers and influence vortex shedding based on the rod size and location. The optimal configuration for minimizing near-wake disturbances has been found in the C3 configuration.