Research on 3-D motion simulation of mooring buoy system under the effect of wave

A mooring buoy system usually contains a tether and a buoy. The mathematical model of mooring system should be developed to research the three-dimensional motion of the mooring buoy system under the effect of wave force. Based on the Newton’s Second Law, a motion governing equation of tether is established. Moreover a discrete motion equation of tether is deduced through the lumped mass method. According to the momentum and angular momentum theories of rigid body, a motion governing equation of buoy is developed. The tether model and the buoy model constitute the three-dimensional motion mathematical model of the mooring buoy system together with the added corresponding boundary condition. The three-dimensional motion of a single- point mooring buoy system is simulated respectively under two level sea condition and four level sea condition. The results show that the single-point mooring buoy system regularly sways near the initial position under the effect of wave force and achieves a dynamic steady state after a period of time.