Computational Fluid Dynamics (CFD) simulation methodologies for FPSO sidewall green-water prediction were consolidated in a Joint Development Project (JDP). To validate the proposed simulation method, a series of model test was performed for sidewall green-water problem of a FPSO in irregular waves. It is confirmed that sidewall green-water prediction using the consolidated CFD simulation guideline are fairly good in overall physical process and relative wave motions, but further development will be required to obtain the reliable results regarding the water height on deck and green-water loads on the pillar.


Under extreme wave conditions, floating offshore structure will exhibit large motion responses and be exposed to various wave impact loads at the same time. In particular, when the relative wave height is higher than the freeboard of the structures, green water may also occur on the deck. It is well known that those green water events can cause fatal damage on the offshore structure and safety of operators. Thus, in the design phase of the offshore structure, it is very important to accurately estimate the green-water occurrence and the resulting impact load.

Regarding the green water problem, nonlinear wave-body interaction effect is a key parameter for the prediction. When the floating body encounters high waves, the scattered wave fields of highly nonlinear properties are developed near the hull while the floater experience large vertical motions. As a result, high relative wave motion (elevation) exceeds the deck height and green-water propagates on the deck. Most of the studies for the green water performed by experimental method. (Newton, 1959, Hong et al., 1993) Vestbostad (1999) observed the sidewall green-water phenomena in regular wave of 100 year design condition. In case of the moored FPSO, not only head sea but also quartering sea can be encountered frequently. In this case, the problem of sidewall green-water needs to be considered significantly. Buchner (2002) performed model test for sidewall green water. The wave headings of 15 degree and 30 degree were applied and the relative wave height was measured at longitudinal side along the hull in regular and irregular waves. In recent years, the CFD methods have been widely applied to the green-water problems of the offshore structures. Ruggeri et al. (2015) presented the CFD simulation results on the green water problems of FPSO under regular wave conditions in beam and bow quartering sea. Compared with the experiments, they reported that the CFD calculations over-predict the wave height rather than experiments. Silva et al. (2016) also applied CFD method for the green water problem of barge-shaped FPSO in oblique waves.

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