Application of active nonlinear energy sink to reduce the oscillations of flow exposed circular cylinder

In this paper, passive and active vortex-induced vibration control of a circular cylinder that oscillates freely in longitudinal and transverse directions is investigated by utilization of nonlinear energy sink. The nonlinear energy sink is composed of a mass, a damping and a nonlinear spring that attaches inside of vibrating cylinder. The vibrational energy of the main cylinder is transferred to the adsorbent mass, thereby reducing the cylinder oscillations. The effectiveness of the proposed control method, numerical results are presented for four Reynolds numbers located in the lock-in region, Re = 85, 90, 95, 100. According to the numerical simulations, the optimized parameters for the passive nonlinear energy sink are considered equal to ... . It can be seen that at all Reynolds numbers, active nonlinear energy sink perform better than passive energy absorbers in reducing vortex-induced vibrations.