Theoretical and CFD investigation on nonlinear dynamics of a cable under vortex-induced vibration with different aerodynamic shapes

Abstract

This paper investigates the effect of the aerodynamic shape on nonlinear dynamics of a cable induced by vortex-induced vibration (VIV) with theoretical and computational fluid dynamics (CFD) method. Firstly, a two-dimensional (2-D) CFD model is established and calculated by using the shear stress transport (SST) k-ω model to supply the necessary drag and lift coefficients for perturbation analysis. Secondly, the planar transverse vibration equation of the cable is established and the wind load is described by the van der Pol wake oscillator. Then, the above two equations are discretized by the Galerkin method, and the modulation equations are obtained by the multiscale method. The results are verified by Runge-Kutta method. Thereafter, three different aerodynamic shapes of the cable are considered and five wind attack angles are defined to extensively investigate the influence on nonlinear dynamic behaviors. The results show that the variation of the cable cross-section significantly changes its aerodynamic performance, and the aerodynamic coefficient of the asymmetric structure is very sensitive to the wind attack angle. Arranging aerodynamic measures (such as soft tail) in the downwind of the cable can effectively reduce the aerodynamic coefficient and dynamic response of the structure.