Theoretical and Experimental Prediction of the Response of Compliant Risers

The general three-dimensional linearised dynamic equations of a compliant riser, idealised as a rotationally non-uniform rod, around a nonlinear static configuration in the presence of general current and monochromatic wave excitation are formulated. Nonlinear forces such as quadratic drag are harmonically linearised by minimising the mean square error between the linear approximation and the nonlinear force. The theory is implemented in a computer program which allows analysis of a variety of compliant riser configurations. Numerical examples and comparisons with time domain solutions for catenary risers are included. Comparisons of our theoretical predictions with experimental results are also presented to evaluate our ability to predict the response of compliant riser systems.