Numerical analysis on pipeline laying for intake deep ocean water

Abstract

This paper is concerned with a numerical simulation of laying a pipeline for intake of deep ocean water. An implicit finite difference algorithm is employed for three-dimensional dynamic equations of a pipe. Geometric nonlinearity and bending stiffness are considered and the equation is solved by Newton-Raphson iteration technique. The dynamic behavior of the laying pipeline is analyzed including pretension, pay-out rate, and seabed slope. In the case of a flat seabed, a touch down velocity is fast at the initial laying stage due to pretension loss and then gradually approaches to a steady-state condition. For the flat seabed, the top tension also greatly decreases when the pipe touches down the sea bottom and then gradually approaches to a steady-state condition. Meanwhile, when the seabed has a slope, the variation of the touch down velocity is nearly regular because the pretension effect is not large. The result shows that some attention needs to be paid when a laying pipeline touches down on a flat seabed Copyright ？ 2005 by The International Society of Offshore and Polar Engineers.