An energy-conserving two-way coupled mode model for underwater acoustic propagation

In order to avoid the energy non-conservation in two-way sound field calculation, which results from cer- tain approximations of non-horizontal boundaries, an energy-conserving two-way coupled mode propagation model is developed. During the deriving of this model, the non-horizontal boundary condition is considered strictly instead of approximately. The coupling equations, which are easy to numerical implementation, are derived from the equation of motion and the equation of continuity. Moreover, the veracity of this model is proved by several numerical examples of different bottom parameters and the equation of energy conservation. It is shown that a boundary correcting term is involved in this model due to the strict formulizing of the boundary condition. And this boundary correcting term guarantees the coupling coefficients be symmetrical and makes the sound field satisfy the law of conservation of energy. Thus, the energy-conserving coupled model is able to handle non-horizontal boundaries adequately, and the two-way sound field in a non-horizontal stratified media can be calculated exactly by this model.