SPH method for long-time simulations of sloshing flows in LNG tanks

The present work is dedicated to the numerical investigation of sloshing flows inside a ship LNG fuel tank. Long time simulations, involving 3-hours real-time duration with realistic severe sea-state forcing, have been performed using a parallel CFD solver running for several weeks on a dedicated cluster. The numerical model adopted is the Smoothed Particle Hydrodynamics model (SPH). This model has been chosen for its Lagrangian approach and for the intrinsic properties of mass and momenta conservation which makes it well adapted for the simulation of violent free-surface flows. The adopted SPH method relies on a Riemann Solver for the calculation of the particle interactions which increases the stability of the scheme and allows for accurate predictions of the pressure during water impact stages. Three different filling height conditions are considered. For all of them energetic sloshing flows are induced with the occurrence of several water impact events. The latter are focused on specific zones of the tank depending on the considered filling height. For some conditions the SPH pressure predictions are compared with experimental ones. A critical discussion of these predictions is performed, highlighting the cases in which the numerical solver is able to provide good local pressure estimations.