ABSTRACT

This study considers the motion responses of multiple adjacent floating bodies in waves. In order to find a solution, a three-dimensional Rankine panel method is adopted in the time domain. In order to obtain validation of the developed numerical method, the motions are estimated of two adjacent Series 60 hulls and a ship-barge model. The computational results are compared with other numerical and experimental analyses, and they showed a favorable concurrence. It was also discovered that the distance between ships affects the motion responses of multiple bodies.

INTRODUCTION

A multiple-body problem requires a solution to the cause of the motion and forces of adjacent multiple bodies in waves. Recently, since an LNG has been developed as an alternative energy resource, the relative motion between the LNG-FPSO and the LNG carriers became an important issue in the multiple-body problem. Related research is therefore currently being carried out. Ohkusu (1974) first solved the multiple-body problem, while Oortmerssen (1979) applied the 3-D sink-source method. Kodan (1984) measured the motions of an adjacent barge and ship in waves.

Currently, a strip theory has been applied to solve the multiple-body problem. As the computational capacity has evolved, 3-dimensional approaches have become popular and the wave green function (WGF), and the higher-order boundary element method (HOBEM) have been applied by Chen and Fang (2000) and Choi and Hong (2002). Kim (2003) applied a unified theory, and Kashiwagi et al. (2005) measured the mean drift forces on the Wigley and barge problem. Recently, Zhang (2007) applied the Rankine panel method (RPM) to the multiplebody problem. All of the numerical schemes, with the exception of the Rankine panel method, are limited to a linear problem, because they are based on frequency-domain solutions. An impulse response function (IRF), which is regarded as a time-domain approach, also uses frequency-domain solutions.

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