Analysis of vortex-induced vibration of an elastic cylinder and influence parameters at low Reynolds number

Through numerical simulation based on the Fluent, the Vortex-induced vibration of an elastic cylinder in uniform flow with Re=200 was obtained by solving the incompressible viscous fluid N-S equations. The cylinder motion was modeled by a mass-spring-damper system, and the motion equation of the cylinder was solved by Newmark-β method which was manually written into the User Defined Functions of Fluent. To realize the nonlinear coupling between cylinder and flow, the dynamic mesh technique was utilized. The dependences of the characteristic value of both the vortex induced force coefficient and the cylinder's displacement, the wake structure on the frequency ratio were analyzed in detail, respectively. The results including "phase switch", "beat" phenomena were obtained successfully. When the influence of streamwise vibration on transverse vibration is taken into consideration, the maximum amplitude of transverse vibration is 0.65 times the diameter. Either of the increment of mass ratio and reduced damping will nonlinearly reduce both the streamwise and transverse vibration as long as the frequency ratio remain unchanged; however, the increment of the mass ratio can control the average displacement deviation of streamwise vibration more effectively.