Abstract

We propose a method to reproduce the encountered ocean wave field by a ship in the experimental wave basin from the wave elevation observed on board of a ship discontiguously in space and time, based on the linear theory. The mathematical wave model is based on the Bessel function for a circular wave basin and estimated its parameters by the least square method. Wave elevation is assumed to be observed by the 3D camera and image analysis system equipped on board. This method and the mathematical model are validated with the results of numerical calculations and tank experiments.

INTRODUCTION

Naito et al. (1999) developed the circular wave basin (AMOEBA) with 50 element absorbing wave-makers installed all around the wave basin. Although it is a small basin with a diameter of 1.6 m and a water depth of 0.25 m, each wave-maker can be controlled independently, and arbitrary wave field can be reproduced in the basin. After that, large wave basins with the same concept were constructed at the National Maritime Research Institute of Japan (Tanizawa, 2013), the University of Sao Paulo (de Mello et al., 2013), the University of Edinburgh (Draycott, S et al., 2015), etc., and are practically used for performance evaluation and research and development of ships and marine structures.

All of the experimental wave basins are characterized by being able to generate arbitrary wave field due to their high wave-making performance, and can generate time-controlled waves at fixed points or stochastically controlled multidirectional irregular waves. As for ships, the former is mainly used to investigate maximal ship motion and structural response. The latter is used to estimate the mean added resistance in waves by the towing experiment or the mean added ship propulsive power in waves by the free running experiment.

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