The dynamics of LNGC and FSRU motions coupled with sloshing is simulated. The motions of two bodies are solved in the time domain by taking account of memory effects. The sloshing is simulated by a Navier-Stokes equation. For the analysis of violent free surface flow due to sloshing, Volume of Fluid (VOF) technique is adopted. The ship motions and sloshing are linked by explicitly coupling the ship motion and sloshing force. The coupled method is verified by comparing the results of free roll decay with the experimental results. The developed method is used to simulate the interaction of side-by-side moored LNG FSRU and LNGC for various partial loading conditions. The effect of sloshing on the two body interaction is studied.
With the rapidly increasing needs of natural gas over the world, one of hot issues in LNG (Liquefied Natural Gas) industry has been moving from LNG carriers to LNG terminals. LNG terminals have been constructed onshore where frequent loading and offloading operations can be effectively carried out. Recently a concept of using floating LNG terminals in offshore attracts the attention of LNG industries. In environment and safety terms, floating terminals have advantages as compared with land based terminals; no money for land, no NIMBY, short construction time, etc. A key issue for any offshore LNG terminals is assurance of safe and reliable transfer of LNG from LNGC to FSRU (Floating Storage and Re-gasification Unit) or from LNGFPSO to LNGC. The LNG offloading and loading operation is affected by many factors, including the sea state conditions, the mooring system, the fender arrangement, loading arm, loading conditions and hydrodynamic interactions between two bodies. Offloading operation is usually performed in side-by-side mooring configuration. In the side-by-side mooring configuration, the distance between two bodies is very small and a violent hydrodynamic interaction can occur due to the resonance of trapped water known as Helmholtz resonance (Hong et al., 2002).