Physical Modeling of Underwater Acoustics

In the attempt to explain underwater acoustic phenomena and to exploit these phenomena in useful ways a number of techniques for analysis have been developed. These include, but are not limited to, mathematical analysis, numerical modeling, in situ empirical description, and physical modeling. All have made substantial contributions to our understanding of the way in which sound behaves in water. The purpose of this chapter is to review the methods and results of physical modeling and to discuss its role in underwater acoustic research. To do this an attempt will be made to define the technique and to set in perspective its relationship to the other methods of analysis. Some attention will be paid to the use of small natural bodies of water, lakes and bays, for example, as model facilities. However, the main thrust of the discussion will be concerned with artificially constructed model tanks and particularly with the study of surface scattering in such facilities. Physical model research has been conducted for some time in a number of contexts. Unfortunately, until the present there has been little communication among various investigators on matters of technique. By discussing the development of physical model experimental methods and illustrating the degree of precision and flexibility possible in model tanks this chapter seeks to encourage and facilitate a more widespread and systematic employment of physical modeling in future underwater acoustic research.