Numerical green water assessment for an FPSO with consideration of nonlinear effects from bilge keel, spread mooring and asymmetric risers

Many researches about green water on FPSO tend to ignore or simplify details like bilge keel, mooring and risers, leaving some gap between academic study and industrial application. This paper presents an efficient numerical approach in frequency domain for FPSO green water assessment, considering nonlinear effects from bilge keels, spread mooring and asymmetrically arranged risers. Comparisons with experimental measurements show that the adequacy of relative motion response prediction is significantly improved by incorporating the equivalent nonlinear effects. Numerical analysis indicates that the green water from sides of the FPSO in oblique and beam sea waves are affected by the presented effects. Application and discussion are further made on the freeboard exceeding frequency at various locations on the FPSO.