Liquid sloshing is quite a common phenomenon in the field of naval architecture and ocean engineering, which is usually accompanied with violent changes, breakups of the free surface as well as strong coupled fluid–structure interactions, and characterized with strong nonlinearity and randomness. Liquid sloshing can not only affect the stability of ships or marine structures, but also can cause damages to the structure. Especially with the size of the liquid cargo carriers growing larger and larger, it is of great significance and a great challenge for both theoretical models and traditional numerical algorithms. As a meshless method, Moving Particle Semi–implicit method (MPS) adopts separate Lagrangian particles to replace the traditional mesh, each of which carries its own physical information and interacts with other particles by a kernel function. Therefore, it has unique advantages in dealing with such large deformation problems because of its self–adaptiveness. In this paper, two improvements were introduced to the original MPS, then the improved MPS was applied to solving two–dimensional liquid tank sloshing problems. At first, focusing on the accuracy and stability of MPS algorithm, the arc method and a collision model were introduced to reduce the unphysical pressure fluctuations resulted from the misadjustment of free surface particles and two particles getting too close. Secondly, the improved MPS was proved to be feasible and advantageous in liquid sloshing problems by comparation with the results of experiments, VOF and SPH methods. Furthermore, the laws of impact pressure and wave elevation change of the liquid tank were investigated under forced rolling and swaying with different excitation frequencies and angles. Finally, the coupled motion of swaying and rolling motion with different loading rates were studied, which is aiming to provide some reference for further study on the influence of the sloshing impact loads on the motion of real ships.
The phenomenon of liquid sloshing always happens to ships with partially liquid–filled tanks under external excitation (Watts, 1885). Large–amplitude sloshing motions can not only reduce the ship’s global stability, but also produce a huge impact force on the wall in the severe sea condition, which can cause local structural damages, and can further result in leakage of oil, or even overturn of ships. This can lead to serious casualties, economic losses and ecological damage as well. In addition, with the trend of LNG’s rapid and large-scale development, liquid sloshing becomes a great threat to the structural strength and security of ships. Therefore, it is quite significant and necessary to study the performance and mechanism of large–amplitude liquid sloshing problems.
