Motions of Floating Body in Transient Waves

Abstract

The characteristics of motions of a floating body in transient waves are investigated by physical and mathematical model. Having calculated slow drift wave forces, non-linear response of a floating body in transient waves can be solved by time domain calculation method. The mathematical model is verified by comparison with physical model tests including long period oscillations. Qualitative properties of the long period motion in transient waves can be simulated by the mathematical model. The agreements of mathematical and experimental results of the maximum amplitude of short period motions are fairly well. Motions of floating body by transient waves and monochromatic waves are compared. The nondimensional maximum amplitude of short period motions divided by maximum wave height in transient waves are almost equal to the nondimensional motions in monochromatic waves at the same frequency without the resonance state. The motions in transient waves are less than the monochromatic motions near the resonance period, and the tendency is heigh when a damping of motion and a number of carrier waves in transient waves are small.