Green Sea and Water Impact on FPSO: Numerical Predictions Validated Against Model Tests

A recently developed numerical design method for analysis of green sea events and resulting impact loads on deck structures of FPSO’s, is validated against model test data. Steep irregular wave conditions are considered, and numerical time series reconstructions are made using the measured wave as input. A second-order numerical random wave description is combined with standard 3D wave diffraction and related vessel motions to predict the relative wave kinematics. A modified shallow water formulation is applied for the prediction of the propagation on deck, and resulting local pressures on the deck-house are estimated by a similarity solution. From this an analysis of the structural integrity can be made. Comparisons to the experiments are made for the relative wave amplitudes, water propagation on deck, and the resulting deck-house loads. A reasonably good agreement is observed for the reconstructions, in a statistical sense, but also for individual events. Thus selected green sea events are investigated in detail, and characteristics identified. The agreement with the model tests is promising especially on the background of the simplified approach used, as well as the expected statistical scatter.Copyright © 2002 by ASME