Abstract
The problem of interaction among multiple floating cylinders which are fixed in waves and current is considered. The current velocity is assumed small. The problem is linearized based on a small parameter τ= ωU/g. Problems of different orders are solved for single cylinder to determine the diffraction property of the cylinder, which gives the relationship between the incident wave amplitude and the diffracted wave amplitude. The resuls are then applied to the problems of multiple cylinders. The interaction among cylinders is represented by some additional incident waves emitted from the other cylinders towards the one under consideration. Different from the previous work in which only the cylinders mounted to the sea bottom are considered, the evanescent wave modes are included in the present work when this method is applied to the floating cylinders. After solving the velocity potential near each cylinder, the hydrodynamic forces can be calculated by integrating the pressure along the wetted surface of each cylinder. It turns out that current and steady potential have a strong effect on the wave-drifting force. The present work also gives a way to evaluate the wave-drifting damping which plays an important role in the slow drift oscillation of moored ocean structures.
