engleski

Transfer functions of nonlinear motion for ship advancing in head seas

The non-linear effects of large motion, caused by added mass, damping coefficients, exciting force and restoring force change with time, cannot be neglected. When an incoming wave approaches the body, an instantaneous draft is computed, and the draft respective coefficients are interpolated using linear regression method. The equations of non-linear motion of ship in head waves are formulated in the paper. The wave is described by linear theory. To solve the coupled time-dependent equations of motion, the trigonometric series method is developed. The comparison of results with experimental values and with the values obtained by fourth-order Runge-Kutta method confirms the numerical results. Compared with Runge-Kutta method the developed technique is faster, shows better stability and the obtained results are functions of time. Transfer functions and absolute and relative motions obtained by non-linear calculation model are compared with the values obtained by linear calculation model.

nonlinear-motion; seakeeping; transfer functions

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