Passive elimination of flow-induced forces and vibrations of a circular cylinder using a slit

Here, passive flow control technique of incorporating a slit through a circular structure is utilized to dampen the flow-induced vibration (FIV). The study is segregated into two main sections, one where the effect of slit width ratio (S/D) and Reynolds number (Re) is investigated on the fixed stationary cylinder, and the other where the effect of slit size is explored on the behavior of the elastically mounted cylinder with varying reduced velocities (Ur) at Re = 100. The slit width ratio is varied from 0% (no slit) to 50% and Re from 100 to 300 for a stationary cylinder. For elastically mounted cylinder, the mass (m* = 5) and damping (ζ = 0.01) ratios and Re (100) are fixed, whereas Ur is varied from 0 to 10. The results are expressed as coefficient of lift and drag, Strouhal number, amplitude and frequency of vibration, force-displacement plots, and vorticity contours. They indicate that the presence of a slit reduces the lift and drag coefficients and suppresses the FIV. At Re = 100, the presence of 10% and 20% slit decreases the lift coefficient by 13.0% and 71.8%, respectively, as compared to the solid cylinder. Considering the maximum amplitude of vibration, a 10% slit resulted in a 5.7% amplitude drop, whilst a 20% slit resulted in a significant drop of 34.4% as compared to the solid cylinder. Further increasing the slit size from 20% to 30% completely vanished the vortex shedding and led to steady flow with zero lift and no vibration.