Comparisons of Simulation Methods for Motions of a Moored Body in Waves

Abstract

Based on the linear water wave theory, numerical simulations are carried out for motions in waves of a body moored by a nonlinear-type mooring system. Numerical results obtained by using the equation of motion described in the time domain with a convolution integral (C.I. method) are compared with those of the second-order linear differential equation with constant coefficients (C. C. method). These results are also compared with experimental values measured from the initial stage when the action of exciting forces starts and the validity of C.I. method is discussed.

Capsize criteria for ship models with memory-dependent hydrodynamics and random excitation

“…The time-and frequency-domain descriptions of rolling motion are connected to each other through the following relation (Ogilvie 1964;Takagi et al . 1984): (1) (1 )) and linear damping (B44 (!…”

“…and B 44 (!) are no longer constant and (2.1) is an approximation (see Takagi et al . 1984;Jiang et al .…”

“…¡ B 44 (1) are also even and the negative frequency domain is omitted in gure 1. The Fourier transform of memory function K(½ ) is related to the hydrodynamic coe¯cients as follows (Takagi et al 1984):…”

“…The direct integration method is used by Takagi et al . (1984) in their study of motions of moored bodies.…”

“…transform of the memory function K (½ ) is given by (see, for example,Takagi et al 1984)K (!) = B 44 (!)…”