Prediction of the Dynamic Response of a Long Flexible Riser under External and Internal Flow: Integral Transform Solution

This paper aimed to analyze the dynamic response of a pinned-pinned riser subject to external and internal flow using the generalized integral technique (GITT). A nonlinear wake oscillator model is used to simulate the drag and lift force on the riser, and coupling with the vibration equation to form the second-order partial Differential Equations (PDEs). The PDEs system can be transformed into Ordinary Differential Equations (ODEs) employing the GITT approach. The influence of the internal flow and external flow are evaluated to show that both these two variables should not be negligible in numerical simulation of the dynamic response of a long flexible riser. The vibration amplitude, frequency and mode number are affected by the flow velocities, and mode transformation can be found in the variation of the internal and external flow velocities.