Non-Linear Time Domain Simulation of Dynamic Instabilities in Longitudinal Waves

A time domain numerical simulation method is developed to determine ship motions in six degrees-of-freedom and to detect dynamic instabilities in both regular and irregular longitudinal waves. The basic approach of the simulation program involves computation of hydrodynamic coefficients of added mass and damping, restoring coefficients and diffraction and Froude-Krylov excitation forces at each step in time according to the instantaneous waterline and vessel position, using a strip theory method and a pressure integration technique along the segments. This paper briefly describes the computational technique utilized and makes comparisons between numerical and experimental roll damping data to infer about its influence on roll amplitude under parametric rolling conditions. An investigation into the dynamic stability in waves of a container vessel example.