title: A perfectly matched layer for fluid-solid problems: Application to ocean-acoustics simulations with solid ocean bottoms.
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.
authors.affiliation: Institute of Engineering Mechanics, China Earthquake Administration, Harbin 150080, China.
authors.forename: Zhinan
authors.initials: Z
authors.lastname: Xie
authors.affiliation: Department of Mechanical Engineering, Solid Mechanics, Technical University of Denmark, DK-2800 Kgs. Lyngby, Denmark.
authors.forename: René
authors.initials: R
authors.lastname: Matzen
authors.affiliation: LMA, CNRS UPR 7051, Aix-Marseille University, Centrale Marseille, 13453 Marseille cedex 13, France.
authors.forename: Paul
authors.initials: P
authors.lastname: Cristini
authors.affiliation: LMA, CNRS UPR 7051, Aix-Marseille University, Centrale Marseille, 13453 Marseille cedex 13, France.
authors.forename: Dimitri
authors.initials: D
authors.lastname: Komatitsch
authors.affiliation: GET, CNRS UMR 5563, Université Toulouse III Paul Sabatier, Observatoire Midi-Pyrénées, 14 avenue Édouard Belin, 31400 Toulouse, France.
authors.forename: Roland
authors.initials: R
authors.lastname: Martin