ABSTRACT:

In this paper, from the viewpoint of thrust generation by waves, we discuss the fluid dynamics of two phenomena. One is a thrust generation by hydrofoil placed at the bow under water of a ship, and the other is a negative drift force acting on a floating oscillating water column (OWC) type wave energy converter "Backward Bent Duct Buoy (BBDB)" in particular wave frequency range. A foil among waves can produce thrust. This may be utilized into ship propulsion in waves and reduction of mooring force of an ocean platform. We discuss the possibility of applying this phenomenon to ship propulsion and reduction of mooring forces. In regard to BBDB, the mechanism of thrust generation and its characteristics are investigated by 2-D and 3-D tank tests and it is shown that this characteristic is very useful to reduce the wave drift force acting on BBDB in irregular waves.

INTRODUCTION

In this paper, from the viewpoint of thrust generation by waves, we discuss the fluid dynamics of two phenomena. One is a thrust generation by hydrofoil placed at the bow under water of a ship, and the other is a negative drift force acting on a floating oscillating water column (OWC) type wave energy converter "Backward Bent Duct Buoy (BBDB)" in particular wave frequency range. Generally speaking, resistance of a ship becomes bigger in waves than in calm water. This phenomenon is well known to naval architects as the resistance increase of a ship in waves. According to the contemporary report, he really built two boats of 13 ft and 24 ft in length named Autonaut as shown in Fig. l, and the boat could move of their own motions due to waves against wind and wave at a speed of three to four knots.

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