Deterministic wave model for short-crested ocean waves: Part I. Theory and numerical scheme

摘要

A directional hybrid wave model (DHWM) hasbeen developed for deterministic prediction of short-crestedirregular ocean waves. In using the DHWM, a measured wavefield is first decomposed into its free-wave components based onas few as three point measurements. Then the wave properties arepredicted in the vicinity of the measurements based on thedecomposed free-wave components. Effects of nonlinearinteractions among the free-wave components up to second orderin wave steepness are considered in both decomposition andprediction. While the prediction scheme is straightforward, thedecomposition scheme is innovative and accomplished throughan iterative process involving three major steps. The extendedmaximum likelihood method is employed to determine thedirectional wave spreading; the initial phases of directional free-wave components are determined using a least-square fittingscheme; and nonlinear effects are computed using bothconventional and phase modulation methods to achieve fastconvergence. The free-wave components are obtained after thenonlinear effects being decoupled from the measurements.Variety of numerical tests have been conducted, indicating thatthe DHWM is convergent and reliable.