The near-bed submarine pipeline is a widely used structure in the marine engineering. Due to the presence of the seabed resulting in an asymmetric flow, a large negative lift (attraction) can be induced on a pipeline in a horizontal current, which has significant influence on the behaviours of the pipeline. A coupled numerical approach is proposed in this paper to assess the nonlinear dynamic responses of this pipeline by combining the meshless technique and the boundary element method (BEM). BEM is firstly used to get the nonlinear dynamic fluid loading induced by the asymmetric flow. The meshless technique is used to discretize the structure of the pipeline, and the local weighted weak form using the spline weight function is employed to get the discrete system of equations for this nonlinear dynamic analysis. A numerical example for the static and dynamic analyses of a structure is firstly presented to verify the effectivity of the present method. Then, the coupled technique is used to simulate the nonlinear dynamic fluid-structure interaction problem of a near-bed pipeline. A Newton-Raphson iteration procedure is used herein to solve the nonlinear system of equations, and the Newmark method is adopted for the time integration. Our studies reveal that there exists a critical current velocity, above which the pipeline will become instable sharply. The detailed relationship between the critical velocity and the gap is given, and it has been found that the critical velocity is significantly affected by the initial gap from the pipeline to seabed. It has demonstrated that present approach is very effective to obtain numerical solutions for the nonlinear dynamic fluid-structure interaction analysis of a near-bed submarine pipeline.
展开▼
