A new nonlinear model of TLP's tendon is presented and its VIV response in effect of current load is simulated considering the hull's motions effects on boundary condition and tension of tendon. Different tensions are considered to affect the VIV response. The Morison equation is used to solve the y-direction time-dependent force exerted on the tendon moving in the fluid. The CFD program FLUENT is used to solve the current force of tendon using 2D model. The finite element method is used to figure out the nonlinear response of tendon. The results show that the changing of tension has significant effects to tendon's VIV response.
Tension leg platform (TLP) is one main type platform used in deepwater oil and gas development. It has accomplished technology and steady capability. There are many studies about TLP, such as study of TLP's types, study of TLP's mounting, study of TLP's analysis method (Rossit et al, 1996), study of TLP's fatigue and reliability (Skogvang and Vogel, 1997), etc. Tendon will have vortex-induced vibration response in current load. The hull's motion will change tendon's boundary conditions and tension, and then influence the response of tendon's vortex-induced vibration. Therefore, a study on vortexinduced vibration of tendon considering the effect of hull's motion is beneficial to the further mastery on the performance of TLP. Many scholars have studied the VIV of offshore platform. Allen (1998) presented an overview of deepwater riser vortex-induced vibration analysis. Vandiver (1998) presented an overview about the key limiting issues of current research in the prediction of vortex-induced vibration of marine risers. Triantafyllou (1999), Foulhoux (1994) and Halse (2000) presented the methods of calculation and examination which are acceptable for the actual offshore platforms. Wang Dongyao (1998) presented a time domain analysis for presented for predicting vortexshedding induced transverse vibration of TLP tethers which are subject to wave current and oscillatory displacements at their upper end both in horizontal and vertical directions.
