Oblique Wave Effects on the Hydrodynamic Responses of Side-by-Side Moored FLNG and LNGC

The motion response predictions of side-by-side moored floating liquefied natural gas (FLNG) and liquefied natural gas carrier (LNGC) under oblique waves is critically important to validate operational security. This article studies the hydrodynamic interactions of side-by-side moored FLNG+LNGC under oblique waves by both numerical simulation and model testing. The artificial damping method, calibrated through gap wave elevations measured in model tests, is adopted to simulate the viscous effect in the gap region using the state-of-the-art software HydroStar. The hydrodynamic performances of the side-by-side system under oblique waves are investigated. Relative motions under different wave directions are also investigated, and the resonant phenomena are analyzed through phase shift. The investigations indicate that motion responses of FLNG are less affected by wave directions, whereas the motions of LNGC at the lee side are suppressed due to the shielding effect of FLNG. Relative motions between FLNG and LNGC tend to be amplified with the out-of-phase mode when two vessels oscillate in the opposed directions, induced by gap water resonances at high frequencies, whereas the mode of relative motions induced by roll resonance depends on wave directions and resonance frequencies. (C) 2018 American Society of Civil Engineers.