ABSTRACT

A smoothed particle hydrodynamics (SPH) method is applied for simulating violent sloshing flows in two-dimensional tanks. The SPH method based on the Lagrangian formulation shows realistic behavior with extreme fluid deformation, fragmentation and reunification. In the present study, boundary conditions are improved and re-initialization is used for the prediction of stable pressure field. Numerical simulations are performed for various water depth and frequencies, and the results are compared with existing experimental data and the results of a finite difference method. The comparison shows fair agreement.

INTRODUCTION

Many studies on ship sloshing problem were carried out in 1970's and early 1980's for the design of LNG carriers. Recently, the demand of sloshing analysis is increasing again, mostly due to the design of larger LNG carriers and LNG FPSOs.

In the present study, a smooth particle hydrodynamics (SPH) is applied for two-dimensional violent sloshing flows. After the pioneering work of Monaghan(1994) for water wave problem, the SPH method has been applied for various free surface problems, especially for strongly nonlinear wave problems. Songdong(2002) solved a pressure-Poisson equation, not the state equation, and Colagrossi et al.(2003) considered both one-phase and two-phase flow model to study sloshing and wave problems. They also introduced a re-initialization technique to obtain stable solution. Iglesias et al.(2004) applied the SPH method to 3-D sloshing flows. Oger(2005) proposed a pressure-sensor concept to evaluate stable local pressure, and introduced the results of 2-D wedge entry problem using the SPH method.

The present study, the algorithm based on the assumption of weakly compressible fluid is applied. For the implementation of boundary condition, the concept of ghost particles is adopted. Furthermore, to avoid unphysical large pressure oscillations in space and time, the density field is re-initialized using an accurate interpolation scheme.

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