On the Increased Damping of a Moored Body During Low-Frequency Motions in Waves

Abstract

An estimation method for the increased damping on a moored body in waves which allow simulation of the decay increase of low-frequency motion in waves is described. Emphasis is put on the analytical estimation method for the increased damping due to waves (wave drift damping) on a moored body during low-frequency motion. The estimated increased damping is compared with that of free oscillation tests in waves, and it is shown that the estimation method presented herein is acceptable qualitatively. The low-frequency resonant sway motions of a two-dimensional moored body in regular wave groups are also compared, and the numerical results show a tendency similar to the experiments when the wave drift damping is included in the equation of motion.