Influence of Pulsating Internal Fluid Flow on the Nonlinear Dynamics of Marine Risers

Abstract

In this work, we explore the dynamics of inclined marine risers subjected to pulsating internal fluid flow. The presence of geometric nonlinearities with static deflection makes the response of the inclined riser different from conventional top tension risers when subjected to pulsating flows. At first, the riser model is solved via the Galerkin method, and the results are compared and validated using perturbation analysis. Then, the response of the riser is studied under various parameters and pulsating flow frequencies. The excitation of the riser under pulsating flow fluctuations causes the riser to vibrate at primary and secondary parametric resonances simultaneously. In addition, the multifrequency parametric excitations interact with the inherit competing nonlinearities causing the response of the riser to exhibit a multi-state solution which is further analyzed via statistical analysis to examine the probability of the basin of attraction. The response of the riser reveals rich and complex nonlinear dynamics features such as quasiperiodic and chaotic behaviors.