A DESIGN ASPECT OF RELATIVE WAVE HEIGHTS OF SHIPS IN ABNORMAL SEA BY 3-D SOURCE TECHNIQUE WITH FORWARD SPEED

摘要

This paper deals with the numerical calculations of relative wave heights of ships in abnormal short crested irregular seas. Here for describing the fluid motion, linear potential theory as and 3-D sink-source technique with forward speed has been used to determine hydrodynamic forces for surface ship advancing in waves at constant speed. Nonlinear empirical roll damping has been taken into account in time domain analyses of motion responses of sea going ships in rough seas. The time domain simulations of relative wave heights of typical container ship and bulk carriers of different sizes in short crested irregular waves have been carried out for three different sea states. For the long time simulation of the random sea to meet abnormal sea waves, unequal frequency spacing has been used. The numerical results of the maximum and the significant values of irregular relative wave heights are discussed by comparing with some requirements by a classification society of shipping.