Title
Improved modeling accuracy of the elastic object response by inclusion of higher order scattering
Author
Nijhoff, M.J.J.
Contributor
Papadakis, J.S. (editor)
Bjorno, L. (editor)
Publication year
2014
Abstract
Current methods of automatic target detection and classification using low- to mid- frequency sonar are based on correlating the measured Target In the Environment Response (TIER) of potential targets with the TIERs in a database of known objects. Obtaining experimental TIER measurements of proud, partially and fully buried objects to populate the database is an expensive undertaking. Using numerical predictions of the TIER instead of experimentally gathered data is a potential efficient alternative. In addition, a numerical model also offers insights into the physics involved as an added advantage. Previously, an efficient numerical hybrid method based on Finite Element and Helmholtz Kirchhoff Integral (HKI) models was developed for prediction of the TIER of arbitrarily positioned axially symmetric objects. This hybrid model was successfully tested and validated for a number of cases. However, the main limitations of this hybrid method (besides being restricted to axially symmetric targets) is the neglection of higher order rescattering between the target and the sediment, and the inability to account for discontinuities or changes in the sound speed and density of the medium surrounding the target surface (unless such changes are perpendicular to the axis of symmetry). For certain target/environment combinations, comparison of measurement and model results suggest that higher order re-scattering contributes significantly to some features of the acoustic response. The hybrid model was extended to include higher order re-scattering by successive iterations of running the original model. As part of the approach a novel non-singular HKI method was implemented and successfully extended to work with nonhomogenous media. The resulting hybrid model that includes higher order re-scattering was validated against the results of an experimental test-setup for which higher order rescattering effects are shown to be relevant.
Subject
Physics & Electronics
AS - Acoustics & Sonar
TS - Technical Sciences
Defence Research
Marine
Defence, Safety and Security
Underwater acoustics
Sonar
Target detection and classification
Target In Environment Response,
Multiple Scattering,
Elastic Target Response
To reference this document use:
http://resolver.tudelft.nl/uuid:79b7234e-3c57-421a-88c4-b3481cb0cf27
TNO identifier
508423
Source
Proceedings 2nd International Conference and Exhibition on Underwater Acoustics, UA2014, 22-27 June, Rhodes, Greece, 473-479
Document type
conference paper