Hydrodynamic Forces and Motions in the Time Domain for an Unappended Ship Hull
Defence R and D Canada - Atlantic Dartmouth, NS Canada
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This report describes numerical predictions of hydrodynamic forces and motionsin the time domain for an unappended ship hull in waves. The hydrodynamicforces in the time domain are evaluated using previously computed values in thefrequency domain, which are based on the three-dimensional Green function fora body with zero forward speed. Forward speed effects are included in both thefrequency and time domains using suitable approximations. Due to the underlyingimportance of numerical predictions of hydrodynamic forces in the frequencydomain, attention has been given to their accuracy, robustness, and efficiency.Comparisons between motion predictions in the frequency and time domainsshow excellent agreement, suggesting correct theoretical and numerical implementations.Comparisons of numerical heave and pitch predictions with modeltest data for the frigate HALIFAX show very good agreement. Time domain simulationsof ship motion execute significantly faster than real time, indicating thatthe approach will be practical for modelling and simulation applications.