Modelling and Simulation of Seaways in Deep Water for Simulation of Ship Motions
Defence R and D Canada - Atlantic Dartmouth, NS
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This report presents models of seaways that can be used for simulation of ship motions. The present work assumes deep water, in which ocean wavelengths are less than half the water depth. Seaway models are presented for both regular and random wave conditions, and are given in both fixed and translating axis systems. For regular waves, the nonlinear free surface can be modelled using Stokes second order theory. For both regular and random waves, the influence of the location of the free surface on wave kinematics can be modelled using Wheeler stretching. Commonly used wave spectra and sources of wave climate data are presented as reference information. Sample computations for the frigate HALIFAX illustrate the influence of simulation parameters on predicted RMS motions and required computational time. Required computational time increases significantly when including nonlinear forces from buoyancy and incident waves. In most cases, simulations run faster than real time.