Combined Potential Viscous Flow Numerical Simulation Of Time Domain Ship Motions Coupled With Nonlinear Tank Sloshing

With the energy demand increasing, people have focused on the development of allkinds of marine energy. The development technology of Liquefied natural gas vessel(LNG)and liquefied petroleum gas vessel (LPG) is also rapidly developing in worldwide. Underthe action of the wind and the ocean surface wave, when LNG or LPG vessel sailing in theocean, it will generates multi-DOF motion response. With such multi-DOF motions, thepartially loaded liquid tank which fixed on the vessel will produce varying degrees of tanksloshing phenomenon. If facing severe sea conditions, the corresponding level tanksloshing phenomenon would produce a strong slamming effect to the bulkhead. While,under the combined effect of the static pressure and the hydrodynamic induced by the tanksloshing phenomenon, the ship multi-DOF motions will get varying degrees effect. Suchphenomena will lead to the local structure damaging and ship seakeeping imbalances. So,the tank sloshing phenomenon and it produced various effects should not beunderestimated at engineering fields. This research focuses on different types of numericalcalculation methods of the the time domain ship motion coupled with tank sloshing inwaves,it has a higher value to both theoretical research and engineering applications.Based on the ship motions in waves theory, three-dimensional frequency domainGreen’s function method, fourier transform method, the viscous flow theory, finitevolume method, boundary element method, for the zero speed or low forward speed shipsand floating structures, based on open source CFD code OpenFOAM, this research hasdeveloped an efficient time domain numerical calculation code for solving without speedor low forward speed vessels and marine structures motions in waves coupled withnonlinear tank sloshing phenomenon; through different wave conditions, the research onLNG ship model with liquid tanks was carried out both experimentally and numerically.The results demonstrate that the numerical code developed for ship motion coupled withtank sloshing is correctness and reliability. Because this code is targeted at the situationthat at engineering field often faced ship or floating structure with liquid tank withoutspeed or with low forward speed time-domain motions, and the implementation process isalso emphasis on open source CFD code, so it not very difficulty to implement and also has very broad applications range, so it has highly practical value to the engineering field.For the vessels has a forward speed coupled with liquid tank, which is still in thetheoretical analysis stage, and the numerical calculation is pretty difficult, this researchbased on the time-domain three-dimensional green function method, three-dimensionalfully nonlinear time-domain simple green function method, time domain boundaryelement method, has developed fully time domain numerical calculation code about withforward speed ship motions in waves coupled nonlinear tank sloshing phenomenon. In thispaper, the comprehensive and series of numerical calculation about the S175container shipwith a liquid tank has carried out. For a S175ship with loaded tank, this research hasverify its hydrodynamic coefficients, wave force, and motion response, for prove thevalidity of the numerical calculation code. And the numerical calculations of differentspeed was carried out respectively.Time domain numerical calculation methods proposed in this research, whichabout ship or floating structure with liquid tank motions in waves, whether with speed ornot, are able to completely take into account all factors such as the wave, ship hull,nonlinear tank sloshing and the coupling effect between the tank and the ship.It also beable to clearly shows the tank sloshing affecting global movements of the ship. Besides, italso has pretty highly computational efficiency, so it has a good application prospects.