Objective With the national strategy inclined to the marine field, the utilization of marine energy has become the focus of a large number of experts and scholars. Vortex induced vibration of cylindrical structures will occur in the complex incoming flow environment in the ocean, and its energy efficiency and dynamic characteristics have attracted much attention.

Method Aiming at the vortex induced vibration of wavy cylinder and its application in the field of energy capture, numerical simulation method was used to systematically study the influence mechanism of different wavy geometric parameters (amplitude A/D and wavelength λ/D) on the vibration response, flow field characteristics and energy capture efficiency of the cylinder under two degrees of freedom.

Result It is found that the dynamic response of the cylinder could be differentiated by amplitude and wavelength: the short wavelength (λ/D=0.768) or the combination of "long wavelength and small amplitude" (A/D=0.2, λ/D=2.4) can significantly enhance the transverse vibration; However, increasing the amplitude (A/D=0.3) or using medium wavelength (λ/D=1.2) will suppress the vibration.

Conclusion In terms of energy capture efficiency, the combination of "long wavelength and small amplitude" (A/D=0.2, λ/D=2.4) reaches the peak value of high energy capture efficiency (η=0.40), and the attenuation is the slowest at medium and high reduction speed, showing the optimal broadband stable energy capture characteristics; The combination of short wave length (A/D=0.07, λ/D=0.768) can obtain higher peak value, but the persistence is poor. Compared with the smooth cylinder, the wavy cylinder can control the response through the customization of geometric parameters, and maintain the stable energy capture in a wider speed range.