Computational modeling of acoustic wavefronts propagating in an underwater environment with uncertain parameters

Abstract

High frequency simulation of underwater sound propagation is a vital part of modeling and simulation of acoustic systems for evaluation and performance prediction. Existing simulations use deterministic ray tracing to propagate the acoustic field and simulate uncertainty by varying results according to basic distributions (e.g., adding ”jitter” to ray arrival angle). Rather than incorporate randomness as a form of post-processing, this work seeks to model uncertainty where it exists in the underwater environment where it is easier to specify, and then propagate the relevant random quantities through the system applying stochastic collocation to an existing deterministic model. Further, this work addresses the drawbacks of ray tracing by taking the deterministic method to be a model that computes propagation of entire wavefronts rather than rays, thus maintaining error control over the physical domain. To this end, generalized polynomial chaos expansions are applied to a level-sets based wavefront propagation method to model the effects of uncertain parameters in an underwater environment. This approach allows for not only simple extraction of the process moments, but also yields an expression for the wavefronts in terms of random variables which can readily be simulated. [Work supported by ONR.]