Modelling of nonlinear shoaling based on stochastic evolution equations

Henrik Kofoed-Hansen, Jørgen Hvenekær Rasmussen

    Research output: Contribution to journalJournal articlepeer-review

    Abstract

    A one-dimensional stochastic model is derived to simulate the transformation of wave spectra in shallow water including generation of bound sub- and super-harmonics, near-resonant triad wave interaction and wave breaking. Boussinesq type equations with improved linear dispersion characteristics are recast into evolution equations for the complex amplitudes, and serve as the underlying deterministic model. Next, a set of evolution equations for the cumulants is derived. By formally introducing the well-known Gaussian closure hypothesis, nonlinear evolution equations for the power spectrum and bispectrum are derived. A simple description of depth-induced wave breaking is incorporated in the model equations, assuming that the total rate of dissipation may be distributed in proportion to the spectral energy density on each discrete frequency. The proposed phase-averaged model is compared with experimental data in four different cases as well as with the underlying deterministic model. In general, the agreement is found to be acceptable, even far beyond the region where Gaussianity (Gaussian sea state) may be justified. (C) 1998 Elsevier Science B.V.
    Original languageEnglish
    JournalCoastal Engineering
    Volume33
    Issue number2-3
    Pages (from-to)203-232
    ISSN0378-3839
    DOIs
    Publication statusPublished - 1998

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