Theoretical and experimental prediction of the response of compliant risers.

The general three-dimensional linearized dynamic equations of a compliant riser, idealized as a rotationally non-uniform rod, around a non-linear static configuration in the presence of general current and monochromatic wave excitation are formulated. Non-linear forces such as quadratic drag are harmonically linearized by minimizing the mean square error between the linear approximation and the non-linear 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 obtained from a 1.5 meter catenary compliant riser model excited monochromatically at the top parallel to a constant current are also presented to evaluate our ability to predict the response of compliant riser systems. (A)