Conflicting Requirements Of Speed AndAccuracy In Underwater Acoustics

Abstract

....the art of applying wave theory to the real world is.... the art of finding the best approximations.... Tolstoy 1973 Computational techniques for predicting underwater propagation loss are reviewed with regard to the trade-off between speed and accuracy. Intensive computational methods (e.g. finite element or finite difference solutions) can be used to generate accurate benchmarks, but are impractical for realistic underwater acoustic problems because of their reliance on super-computing resources, particularly for 3D problems. Methods such as the paraxial, adiabatic or WKB approximations are invoked in practice, inevitably sacrificing some accuracy for the necessary speed. This trade-off is at the heart of the efficient solution of practical problems in underwater acoustics. The result is inevitably a compromise, and here we illustrate the importance of making the right choice of method, by comparing the results of different approximations against a standard benchmark solution.