COUPLED DYNAMICS OF TETHERED BUOY SYSTEMS

The three-dimensional coupled behavior during the interaction of buoys with their mooring systems is numerically analyzed. A time-domain mod el was developed to predict the response of a tethered buoy subject to hydrodynamic loadings. External loadings include hydrodynamic forces, tethers tensions, wind loadings and weight. System nonlinearities inc lude large rotational and translational motions, and non-conservative fluid loadings. The mooring problem is formulated as a combined nonlin ear initial-value and two-point-boundary-value problem which is direct ly integrated both in time and space. Buoy equations of motion are der ived using small Eulerian angles. Coupling between rotational and tran slational degrees of freedom is included and coupling between the buoy and cable is effected by adopting the buoy equations of motion as bou ndary conditions at one end for the mooring problem. Numerical example s are provided to validate the formulation and solution technique; pre dicted responses of three types of buoy (sphere, spar, and disc) are c ompared with experimental results. Copyright (C) 1997 Elsevier Science Ltd.