Lloyd Register's (LR) Global Technology Centre in Singapore and Keppel Offshore & Marine Technology Centre (KOMtech) have engaged in a joint research and development project (JDP) to develop advanced numerical simulation capabilities, using high performance computing, to predict semi-submersible behaviour in waves.
LR has developed a numerical tool using "NewWave" which has been applied on fixed offshore structures to simulate wave-in-deck loading. Adapting this tool with KOMtech’s deepwater know-how and both parties’ Computational Fluid Dynamics (CFD), the JDP aims to build advanced capability in the prediction of semi-submersible behaviour in extreme waves through development of "Numerical Wave Basin".
KOMtech’s in-house data from model tests carried out on semi-submersibles will be used to benchmark and validate the developed technology.
Motion and Air Gap Prediction
The accurate prediction of motion and air gap requirements, between maximum wave height and the underside of a platform deck, for the design of deep water semi-submersible platforms for operations in harsh environments and extreme weather conditions is crucial. This is especially the case for operations in areas such as the Arctic, North Sea and Western Australia and other deep sea frontiers.
Real ocean states are complex and difficult to define numerically due to their irregular wave patterns, strong non-linearity and non-Gaussian statistics. This is further complicated by the response of the floating body to the actual wave, making the accurate prediction of the required motion and air gap for the safe operation of a semi-submersible a real challenge.
Current methods make use of model testing to help resolve these issues. This method is time-consuming and requires multiple test runs in attempts to fully capture all possible combinations of the waves and headings. The new numerical method allows fast and efficient way for simulating these conditions.
The project is co-funded by Maritime and Port Authority of Singapore (MPA) under the Maritime Innovation and Technology Fund.
Picture: Semi-submersible drilling rig (CFD modelling) (courtesy of Keppel Offshore and Marine Technology Centre).
