Experimental Study of Sloshing Effects in Roll Motion of Floating Units

Usually, the hydrodynamic loads due to sloshing are considered in the design of liquid cargo ship or floating units concerning the structural. Owing to the increasing size of these structures, resonant sloshing motions may occur and result in the amplification or attenuation of motion of the vessel. In order to assess the effect of sloshing, traditionally the motion of the vessel is calculated at first without considering the dynamic of the liquid inside the tank. After that, this motion of the vessel is inputted as excitation motion acting on the tank and, finally, the sloshing effect is evaluated. In the other words, the coupling effects of sloshing and sea wave in the vessel’s motion are ignored. A bibliographical survey shows that there are few studies that consider the effect of sloshing on the ship motion, acting as a passive device of absorption of the movements. The main goal of this research is to investigate experimentally the roll motion amplification and reduction due to sloshing. The coupling effects of sloshing and sea wave in the vessel’s motion are taking into account by recording the motions, in regular waves, of a free floating model with a partially filled liquid tank. For this purpose, a two-dimensional model is designed to carry out measurements with fixed cargo and partially filled liquid cargo. The experimental results are evaluated by comparing the measured motion of the free-floating model with fixed cargo against the results obtained by traditional approach. Then, the effects of sloshing on floating units are shown by comparison of the measurements from free-floating model with fixed cargo and liquid cargo. The results shown herein provide data for the validation of new numerical approaches for the study of the coupled motions of the floating units and sloshing.