WIAS Preprint No. 1365, (2008)

An optimisation method in inverse acoustic scattering by an elastic obstacle



Authors

  • Elschner, Johannes
  • Hsiao, George C.
  • Rathsfeld, Andreas

2010 Mathematics Subject Classification

  • 35R30 76Q05 35J05

Keywords

  • acoustic and elastic waves, inverse scattering, potential representation, Kirsch-Kress method

Abstract

We consider the interaction between an elastic body and a compressible inviscid fluid, which occupies the unbounded exterior domain. The inverse problem of determining the shape of such an elastic scatterer from the measured far field pattern of the scattered fluid pressure field is of central importance in detecting and identifying submerged objects. Following a method proposed by Kirsch and Kress, we approximate the acoustic and elastodynamic wave by potentials over auxiliary surfaces, and we reformulate the inverse problem as an optimisation problem. The objective function to be minimised is the sum of three terms. The first is the deviation of the approximate far field pattern from the measured one, the second is a regularisation term, and the last a control term for the transmission condition. We prove that the optimisation problem has a solution and that, for the regularisation parameter tending to zero, the minimisers tend to a solution of the inverse problem. In contrast to a numerical method from a previous paper, the presented method does require neither a direct solution method nor an additional treatment of possible Jones modes.

Appeared in

  • SIAM J. Appl. Math., 70 (2009) pp. 168--187.

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