Abstract

Numerical simulations of the sloshing phenomena of the liquid inside of a tank with the regular and irregular tank motions are carried out. An in-house structured CFD solver which is capable the moving grid technique is used. The governing equations are 3D Navier-Stokes equations for the incompressible flow. An interface capturing method based on the single phase level-set approach is employed to capture free surface of the liquid. The LNG tank shape which has the experimental data is utilized. The sway motion of the LNG tank is taken account by the grid velocity which is introduced by the amount of the displacement of the computational grid based on the tank motion. First, the regular sway motion is enforced to examine the occurrence of the swirling phenomena which the liquid rotates inside of the tank, and the time histories of the pressure at the positions on the tank wall are validated. Next, the irregular tank motion which is based on the RAO of the ship motion in irregular waves and the power spectrum of the wave is enforced, and the difference of the hydrodynamic forces of the tank between the regular and irregular motions are examined.