A hybrid method for ship response coupled with sloshing in partially filled tanks

An efficient hybrid numerical method was developed to study wave-induced ship response coupled with sloshing-induced compressible fluid response in partially filled tanks of a 138,000 m(3) liquefied natural gas carrier at zero speed in regular head and beam waves. A nonlinear boundary element Rankine source code, solving the incompressible incident flow field, accounted for the nonlinear stationary forward speed problem and the weakly nonlinear seakeeping problem. A Reynolds-averaged Navier-Stokes equations solver, computing the compressible sloshing flow in tanks, considered the associated discontinuous numerical domains of coupled simulations. Grid sensitivity studies were performed. Comparative available experimental model test measurements of ship response and free surface sloshing elevations in tanks validated the numerical method. Further investigations regarding the influence of wave steepness and tank fill levels on sloshing were performed. Results demonstrated that liquid sloshing in tanks had a large influence on ship surge and roll responses but hardly effected ship heave motions.