Sensitivity Study On Computational Parameters For Prediction of Slosh-induced Impact Pressure

In this study, based on careful observation of experimental data, physics-based numerical models are developed for sloshing flows in ship cargo. The particular scheme of interest is a finite difference method based on the SOLA-SURF method. The technical issues of conventional methods are outlined, and the corresponding remedies are introduced. The present numerical method is validated by comparing computational results with the experimental data measured in model tests. In particular, sensitivity to critical computation parameters, e.g. mesh size and time segment, is observed. The comparison shows a fair agreement of overall fluid motions and hydrodynamic pressures.



INTRODUCTION

Recent activity in building large LNG carriers and designing coastal LNG platforms increases the demand for an accurate prediction of sloshing flow and corresponding hydrodynamic loads. Compared to the studies on sloshing flows of the late ’70s and early’80s, the recent studies have a distinct difference: the analysis tool. That is, most studies now rely on numerical methods. Due to the dramatic development of computational resources in the last 2 decades, numerical skills are widely used in many engineering fields. Further, many CFD codes are available in the commercial market. Despite a mature computational environment, the direct application of numerical techniques to the ship-sloshing problem is not easy. A primary reason is the occurrence of impact on the tank ceiling and side walls. When hydrodynamic impact is involved, a very careful analysis is required. In particular, in our engineering problem, an accurate prediction of slosh-induced loads on ship structures is the ultimate goal of sloshing analysis. We need then to predict the actual magnitude of impact pressure as well as the kinematics of the sloshing flow. For this, the general-purpose computational programs are not considered to be an adequate tool. Some representative studies based on numerical methods have been conducted by Faltinsen (1978), Bridges (1982) and Mikelis (1984).