Hydrodynamic responses of a thin floating disk to regular waves

- Surge, heave and pitch RAOs of thin floating disks experimentally investigated.
- RAOs reduce as incident wave steepness increases for short incident wavelengths.
- RAOs insensitive to incident wave steepness for long incident wavelengths.
- Existing theoretical models shown to predict surge RAOs of same form in long waves.
- Potential-flow/thin-plate model generally predicts RAOs with reasonable accuracy.

The surge, heave and pitch motions of two solitary, thin, floating disks, extracted from laboratory wave basin experiments are presented. The motions are forced by regular incident waves, for a range of wave amplitudes and frequencies. One disk has a barrier attached to its edge to stop the incident waves from washing across its upper surface. It is shown that the motions of the disk without the barrier are smaller than those of the disk with the barrier. Moreover, it is shown that the amplitudes of the motions, relative to the incident amplitude, decrease with increasing incident wave amplitude for the disk without a barrier and for short incident wavelengths. Two theoretical models of the disk motions are considered. One is based on slope-sliding theory and the other on combined linear potential-flow and thin-plate theories. The models are shown to have almost the same form in the long-wavelength regime. The potential-flow/thin-plate model is shown to capture the experimentally measured disk motions with reasonable accuracy.