This paper focuses on sloshing loads acting on partially filled tanks simulated in two-dimensions, i.e. an infinitely long tank. Investigation was carried out first by Finite Element Method (FEM) Computational Fluid Dynamics (CFD) approach, considering the structure as rigid wall. Thereafter, fluid structure interaction (FSI) model using finite element method for both fluid and structural degrees of freedom was implemented. Typical test cases were considered, for which experimental results were available in open literature and already compared with other CFD results in previous works. Comparisons are widely discussed and hints are reported about assumptions and practical issues making such analyses very challenging.
Sloshing phenomenon, as it is well-known, consists in the movement of liquids inside partially filled tanks, which generates dynamic loads on the tank structure. Resulting impact pressures due to this phenomenon are of great importance in assessing structural strength, and their correct evaluation still represents a challenge for the designer due to the high nonlinearities involved, with complex free surface deformations, violent impact phenomena and influence of air trapping. Sloshing pressures are generally evaluated by class rules using semi empirical formulations based on geometrical features of the tank and ship motions amplitudes (pitch and roll angles). Nowadays, marine designers must pay attention to sloshing loads especially when dealing with a LNG carrier (Tveitenes et al 2004, Graczyk et al 2007). Tanks of LNG carriers are indeed always in partial-filling conditions because of the boil-off of the cargo and, in addition, the cargo containment system is more vulnerable to damages caused by sloshing loads. Moreover, designers may use liquid movement in order to damp ship motions, that is the case of passive anti-roll tanks. Such tanks are helpful for ships travelling at low speed that cannot take advantage of the wing support effect of stabilizer fins.
