Using strip theory to model vibrations in offshore risers

Abstract

We present in this paper an algorithm for the coupled time-domain solution of governing equations of flow and those of the structure using the strip theory. We adopt this approach for numerical simulation of the multi-mode response of a flexible long riser to Vortex-Induced Vibrations (VIV). In this research, various models which have been used to solve the riser problem are briefly studied and compared. The work reported here initially includes calculation of eigenvalues and eigenmodes of the riser, the results of which are subsequently used to predict the response of the riser based on a modal analysis. The 2D flow simulations used in the strip theory are validated using experimental and numerical results presented in the literature. The Root Mean Square (RMS) of the amplitude of the riser movement in the cross flow direction for various top tensions is studied and compared with similar cases reported in the literature.