Analysis of the Oscillatory Motions of the Moored Body Scheme A in Waves and Current.

摘要

This report describes a theoretical investigation of the oscillatory motions,stability,and orientation of the Moored Body Scheme A in current and waves. Linear,first order equations for oscillatory motions and cable tension,are developed for a body of revolution moored to the bottom in finite depth water by a single restraining cable. Wave exciting forces and certain hydrodynamic coefficients are developed from potential flow theory,and non-linear viscous damping effects are included in the formulation by an equivalent linearization technique. Surge,sway,pitch,and yaw motion and tension amplitudes are obtained in response to regular and irregular waves for a variety of water depths,cable lengths,and static cable tensions. Equilibrium orientation in waves and currents is established by the current or wave-current interaction depending on the magnitude of body oscillation velocities relative to the current speed. The most prominent feature of the oscillatory motions is the presence of a pitch resonance occurring at a frequency of 0.33radians per second. (Author)