A perfectly matched layer for fluid-solid problems: Application to ocean-acoustics simulations with solid ocean bottoms

Zhinan Xie, René Matzen, Paul Cristini, Dimitri Komatitsch, Roland Martin

    Research output: Contribution to journalJournal articleResearchpeer-review

    Abstract

    A time-domain Legendre spectral-element method is described for full-wave simulation of ocean acoustics models, i.e., coupled fluid-solid problems in unbounded or semi-infinite domains, taking into account shear wave propagation in the ocean bottom. The technique can accommodate range-dependent and depth-dependent wave speed and density, as well as steep ocean floor topography. For truncation of the infinite domain, to efficiently absorb outgoing waves, a fluid-solid complex-frequency-shifted unsplit perfectly matched layer is introduced based on the complex coordinate stretching technique. The complex stretching is rigorously taken into account in the derivation of the fluid-solid matching condition inside the absorbing layer, which has never been done before in the time domain. Two implementations are designed: a convolutional formulation and an auxiliary differential equation formulation because the latter allows for implementation of high-order time schemes, leading to reduced numerical dispersion and dissipation, a topic of importance, in particular, in long-range ocean acoustics simulations. The method is validated for a two dimensional fluid-solid Pekeris waveguide and for a three dimensional seamount model, which shows that the technique is accurate and numerically long-time stable. Compared with widely used paraxial absorbing boundary conditions, the perfectly matched layer is significantly more efficient at absorbing both body waves and interface waves.
    Original languageEnglish
    JournalAcoustical Society of America. Journal
    Volume140
    Issue number1
    Pages (from-to)165-175
    ISSN0001-4966
    DOIs
    Publication statusPublished - 2016

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