Ship Engineering

[Purpose] In order to study the vortex-induced vibration response characteristics of marine risers under the action of ocean currents, [Method] based on computational fluid dynamics(CFD) and computational structural dynamics(CSD), a viscous flow field calculation model is established in the fluid domain using the slicing method and overlapping mesh method, and a three-dimensional calculation model of the riser is established in the riser structural domain using finite element method. The bidirectional and sequential coupling of the fluid domain and the riser structure is achieved by user defined function(UDF) programming, and a numerical model of fluid-structure coupling of pipe vortex-induced vibration is constructed, and the accuracy of the numerical model is verified. [Result] The results indicate that the dimensionless displacements in both the transverse and downstream directions of the riser decrease continuously with the increase of the superimposed flow vibration frequency. The difference is that the decrease in the transverse direction is small, while the decrease in the downstream direction is large. There is a delay effect in the transverse displacement of the riser, and the root mean square value of the dimensionless displacement in the transverse flow during the deceleration phase is much larger than that during the acceleration phase; there is also a delay effect in the displacement changes in the downstream direction. When the displacement of the riser in the downstream direction reaches a relatively stable state, the vibration trajectory is in the shape of an "8". [Conclusion] The research results can provide some references for the design of deep-sea risers.