An approach on calculating mean drifting forces acting on a 3-D floating body under waves and currents

摘要

The mean drifting forces have a relation only to first-order motion responses and first-order forces; therefore, the key to calculate the mean drifting forces is to solve the first-order problem. Under the assumptions of potential flow and low moving speed, the problem of a floating body moving with arbitrary oscillating motions and arbitrary wave directions is modified, and a form of Green function of the simplified equation is derived. The Green function is then expanded into an oscillating source G{sub}0 at zero forward speed and a correction term G{sub}1 to take into account low moving speed, and the expressions for G{sub}0, G{sub}1, △G{sub}0 and △G{sub}1 are then derived. The numerical results of this approach will be compared and discussed. Thc effect of currents to a freely floating body will also be discussed.