Comparative Analysis of Vortex Induced Nonlinear Vibration of Casing Pipe under Three Different Boundary Conditions

The casing pipes are widely used for drilling wells in the ocean. But less investigation on VIV excited by wave-current combination was done for casing pipes in the deep water.In this paper, the vortex-induced nonlinear vibration of casing pipes in deep water was studied considering the loads of current and combined wave-current. The vortex-induced vibration equation of casing pipes was set up with considering the beam mode and Morison’s nonlinear fluid damp as well as the vortex-excited loads under three different boundary conditions.The vortex-excited nonlinear vibration was calculated by using Galerkin’s method.The response including primary resonance induced by current and the composite resonance under combined wave-current for the marine drilling risers of the Donghai 3 were studied. The numerical results show that the dynamic response of marine risers induced by the current is basic and the influence of wave may be neglected.The vortex-induced nonlinear vibration of casing pipes under three different boundary conditions is studied and the complicated response behaviors of casing pipes are described under combined wave-current based on the numerical simulations.