Propagation of Sound from a Fluid Wedge into a Fast Fluid Bottom
Coppens, Alan B.
Sanders, James V.
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When sound propagates up the continental shelf towards the shore, there is a loss of lower frequencies. The distances from the shore at which each frequency is lost correspond closely to the depth at which normal modes in the shallow-water channel would be cut off. After cut-off is reached for a specific frequency, the associated energy in that normal mode is dumped into the bottom forming a highly collimated beam with a shallow angle of depression. This problem is modelled by a wedge of fluid overlying a fast fluid bottom. The method of images is used to calculate the distribution of pressure and its phase at the interface; the interface is then treated as a distribution of sources and the radiated field in the bottom is calculated by the Green's function integral technique. Both calculations require a high-speed digital computer. The results of these programs compare well with laboratory experiments performed at the Naval Postgraduate School. The results of these programs are presently in the process of being analyzed to determine the parametric dependence of the beam on the angle subtended by the wedge and on the properties of the fluids in the wedge and bottom.
Saclantcen Conference Proceedings No. 27
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