ABSTRACT:

The accurate determination of vessel motions and wave loads from the storm wave is one of the most difficult problems. Desktop computers are still not powerful enough for three-dimensional numerical simulation in time domain. In this article, the numerical model based on boundary element method (BEM) is used. For faster simulation the simplified interaction of a vessel and wave surface, and also condensation of nodal unknowns on a free surface is used. Against of other works on Numerical Wave Tank (NWT), free surface is not formed from the wave-maker moving, but is determined from solving separate problem. It is assumed that the ship does not change the form of a free surface. As result it is possible to divide a task: separately to determine parameters of wave movement and to calculate a motion of a ship on given waves.

INTRODUCTION

The determination of vessels and marine structures motion and wave loads on the storm wave is one of the most difficult problems in design and life cycle support. Nowadays, using computer technologies and numerical methods we can solve very complex practical problems. Last two decades the numerical simulators of the marine waves and ship motion on waves, Numerical Wave Tank (NWT), were considerably advanced. The greatest development was received with techniques of computing hydrodynamics on the basis of methods of Volume of Fluids (VOF), proposed by Nichols and Hirt (1977), and boundary elements (BEM), developed in works of Brebbia, Walker (1980) and other researchers. Recently there are many papers dealing with fully nonlinear 3-D numerical wave tank models and codes, for example, Kim and Kim (1997), Tanizawa and Minami (2001), Clauss, Schmittner and Stutz (2003). Method VOF and other finite-difference schemes allow taking into account viscous and some other effects, but requires large computer resources.

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