Approximate Calculation of Low Forward Speed Ship Radiation and Diffraction Wave Patterns

摘要

The present work generalizes a previous procedure for calculating the far field radiation and diffraction waves for a ship at zero speed in the presence of a random sea, to the low forward speed case. The far field waves are calculated by using a Green's function which accounts for linearized terms of the forward speed but neglects higher order terms. This results in a drastic simplification of the arbitrary speed case but retains some of the principal features of forward speed. Extensive calculations are presented for the elevations and slopes of the ship, sea, and superposed waves for various cases of forward speed and sea state. The results are presented in the form of three-dimensional and contour plots. The results show that the effect of forward speed is to increase the magnitudes of the ship waves. Also, forward speed tends to destroy the near symmetry in the ship waves for bow and quartering seas, observed for the zero speed case. Keywords: Low forward speed, Ship radiation, Far field spatial realizations, Random sea waves, Diffraction waves. (mjm)