Time domain analysis of random wave forces on pipelines in the inertia regime

Abstract

An experimental investigation on random wave induced forces on a smooth submarine pipeline, fixed horizontally near a plane boundary, is carried out in the inertia-dominated regime. The water particle kinematics at the centre line of the pipe are generated using linear numerical filters, derived from the time history of water surface elevation. The pipeline was subjected to Pierson-Moskowitz spectrum (P-M spectrum) at various energy levels to achieve different significant wave conditions. The in-line hydrodynamic coefficient of inertia and the transverse hydrodynamic coefficients of lift and vertical inertia are evaluated utilizing the measured forces and through the use of least-squares method in the time domain. These hydrodynamic coefficient are found to be a function of gap ration of the pipeline from the plane boundary and correlate very well with the potential flow results within the range of the Keulegan-Carpenter number or period parameter investigated.