Modeling Acoustic Scattering and Propagation with Elastic Bottoms Using Finite Elements

date February 15, 2013
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Friday, February 15, 2013 4:00 p.m. in ETC 4.150

Dr. Marcia J. Isakson and Dr. Nicholas P. Chotiros
Applied Research Laboratories
The University of Texas at Austin
http://www.arlut.utexas.edu

Acoustic interaction with the ocean bottom is a critical part of understanding propagation in shallow water environments. However, most ocean propagation models consider the seafloor as flat or use approximations to determine the effects of scattering from the rough interface. Each of these approximations has a range of validity which is generally unknown for layered or elastic bottom types with realistic roughness conditions. Elastic bottoms present a unique challenge since scattering from rocky or hard bottoms often produces an interface wave which is not captured in many of the approximations. Finite element analysis provides a useful benchmark for these models since it approaches an exact solution to the Helmholtz equation as the discretization density increases. In this study, finite element models will be compared with perturbation theory and the Kirchhoff approximation for rough elastic bottoms. These results will be used to compute reflection and backscattering coefficients for areas with rocky seafloors.