Intake/discharge effects on the hydrodynamics of floating bodies

The free-surface flow in the presence of a steady intake or discharge flow from the surface of a floating body and ambient waves is studied. The problem is formulated within the assumptions of potential theory by decomposing the total potential into steady and time-harmonic components. The nonlinear free-surface conditions are linearized with respect to the intake or discharge Froude number and the wave steepness. An analysis of the linearized free-surface conditions shows that it is the induced surface current that causes the modification of the ambient flow-field.; The steady component, which is further decomposed into the double-model potential and the perturbation potential, and the time-harmonic component are obtained using the quadratic boundary-element method. The time-harmonic potential is coupled with the steady potentials through the free-surface condition. The double-model potential is obtained by employing the Rankine source and its image about the still-water surface as the Green Function. The Rankine-source boundary-element method is employed to obtain the steady perturbation and time-harmonic potentials. The parallel boundary-element method and the method of sub-regions are proposed to mitigate the computational burden and truncation effects associated with the Rankine source boundary-element method.; The steady flow problem is solved for isolated singularities beneath the still-water line, a circular cylinder and a family of rectangular prisms floating on the still-water line in two-dimensions. In three-dimensions, the steady flow problem is solved for a source beneath the still-water surface and OTEC barges with intake. Results show that there exists an upper-limit on the intake or discharge Froude number beyond which a steady solution might not exist.; Numerical results for the time-harmonic potential show that the intake or discharge flow affects the damping coefficients significantly. The effect of the intake or discharge flow on the added-mass coefficients and hydrodynamic force and moment amplitudes acting on the floating body is insignificant. The mean drift loads in the horizontal plane acting on the floating body are obtained from the momentum approach. It is shown that the steady second-order potential contributes to the mean drift loads. The intake or discharge flow, however, does not contribute significantly to the mean drift loads.