Search

The vortex-induced vibration (VIV) of flexible risers is a complex fluid–structure interaction (FSI) phenomenon. In this study, we conducted a numerical simulation method based on the slicing method to study the vortex-induced vibration (VIV) of deep-sea flexible risers with different slenderness ratios and uniform flow velocities. The method combines the finite element model of the riser structure with the two-dimensional flow field slices solved by the Fluent solver. The fluid–structure interaction was realized by a self-compiled UDF program and the overset mesh technique. The numerical results were validated by comparing them with experimental data. The VIV characteristics of the riser, such as the vibration track, vibration mode, vibration frequency and wake vortex shedding mode, were analyzed. The article reveals the nonlinear dynamic features of flexible riser vibration, such as multi-frequency vibration, wide-frequency vibration and multi-modal vibration. The article also provides insights into the fluid–structure interaction mechanism of VIV of deep-sea flexible risers.

This paper presents a numerical algorithm used together with a Finite-Element based Vortex-Induced Vibration (VIV) prediction software VIVANA to obtain a hydrodynamic force coefficient database based on response measurements of flexible riser VIV model test of staggered buoyancy elements. The excitation coefficient database is parameterized; and the representative parameters are systematically varied in VIVANA simulations until the predicted responses in terms of mode number, response frequency, root-mean-square (RMS) response amplitude, and RMS curvature agree well with the experimental data under same flow and boundary conditions. An optimal set of force coefficient database for both the buoyancy element and the bare riser section is obtained and a significant improvement in VIV prediction by VIVANA is achieved. The obtained hydrodynamic force coefficient database can be also applied to other empirical VIV prediction programs. The sensitivity of using the same database to predict the VIV of different configurations has also been investigated.