Kuznetsov, N. McIver, Maureen McIver, Philip Wave interaction with two-dimensional bodies floating in a two-layer fluid: uniqueness and trapped modes Existing results on the linearised water-wave problem for a homogeneous fluid are extended to the case of a two-layer fluid. In particular, the appropriate form of Mazya’s identity is presented and used to obtain uniqueness results, and examples of geometries are constructed for which trapped modes occur. untagged;Mathematical Sciences not elsewhere classified 2005-08-25
    https://repository.lboro.ac.uk/articles/preprint/Wave_interaction_with_two-dimensional_bodies_floating_in_a_two-layer_fluid_uniqueness_and_trapped_modes/9383399