Numerical Studies of Coupling Effects Between Liquid Sloshing and Ship Motions

A computational tool, based on a hybrid model, for the simulation of the coupling between ship motions and liquid sloshing inside ship tanks is considered. A 3D panel method based on the frequency-domain potential-flow theory is used to evaluate the external flow around the ship hull. Hydrodynamic coefficients and wave loads given by the frequency domain solutions are transformed into the time domain using an inverse Fourier transformation. Due to nonlinearities of the sloshing flow, the equations for the ship motions are formulated and solved in the time domain using the impulse response function (IRF) method. The internal flows inside the tanks are modeled using the two-phase incompressible Reynolds-averaged Navier-Stokes (RANS) equations. A Volume of Fluid (VOF) technique is used to capture the violent flows inside the tanks. The viscous flow solver is developed within the framework of the open source CFD toolkits, OpenFOAM. The ship-motion solver and the sloshing-flow solver are coupled at each iterative time step, i.e., the sloshing impact loads are considered in the ship motion equations, and the movement of the sloshing tanks is determined from the computation of the ship motions. Detailed validations of the computational tool are conducted using experimental results.