International Conference on Computational Methods in Marine Engineering MARINE 2005 L. Delorme, A. Souto Iglesias and S. Abril P´ erez c CIMNE, Barcelona, 2005 SLOSHING LOADS SIMULATION IN LNG TANKERS WITH SPH L. Delorme * , A. Souto Iglesias * and S. Abril P´ erez † * Model Basin, ETSIN, Universidad Polit´ ecnica de Madrid Avda Arco de la Victoria s/n. 28040, Madrid. Spain e-mail: ldelorme@etsin.upm.es, web page: http://canal.etsin.upm.es/ † NAVANTIA Puerto Real Shipyard. Spain e-mail: sabril@izar.es Web page: http://www.navantia.com Key words: Smoothed Particle Hydrodynamics (SPH), Sloshing, LNG tankers, Navier-Stokes simulation. Abstract. In this paper a study on the application of the SPH method to the simulation of the sloshing phenomenon is presented. The sloshing problem in the framework of naval architecture is reviewed, reporting the state of the art of the analytical and numerical models used to simulate this phenomenon. The particular case of LNG tankers is examined for which the forces exerted by the liquid on the tank’s walls are a crucial issue. Different approaches for the prediction of these loads are commented and the advantages and shortcomings of them are discussed. A way to simulate the liquid motion in the tank is to use SPH method (Smooth Particle Hy- drodynamics). SPH is a Lagrangian method invented by Lucy in 1977 in order to simulate astrophysical problems. It has been extended to free surface flows by Monaghan in the eighties 8 and since then, several liquid and solid problems have been successfully simulated with SPH. The method is presented here, stressing the critical points in simulating sloshing phenomena. Treatment of the boundaries is one of the points leading to inaccuracies and has to be improved. We present different ways dealing with the boundaries using SPH and compare the results with those obtained using Lloyd’s Register of Shipping (LRS) program for sloshing for a real case corresponding to a 138.000 m 3 LNG tanker. 1 INTRODUCTION Sloshing can be defined as a dynamic load acting over a tank structure as a result of the motion of a fluid with free surface confined inside the tank. It is a problem of relative importance in the design of marine structures in general but it becomes specially important in some particular cases as the LNG vessels. The increasing traffic of LNG tankers and its growing capacities have imposed the need to accurately predict the loads acting on the structure by using valid methods for the estimation of sloshing effects. 1