Page 38 - \Winter 2015

Computer Simulation for
Predicting Acoustic Scattering from Objects at the Bottom of the Ocean
adequate for several years, but the uniqueness of this type of simulation has spawned an interest in using this technol- ogy in a more aggressive way: doing massive parametric studies of large varieties of possible real-world target/en- vironment scenarios, in order to create statistically robust acoustic signature libraries. Having such a large data base of signatures will help improve the reliability of sonar systems trying to identify an object, irrespective of small variations in construction or different types of surrounding environ- ments. This will require tens of thousands or even hundreds of thousands of templates. To produce that many in a rea- sonable time will require computing at least several hundred templates per day, or a computational speed of only a few minutes per template.
R&D at NSWC PCD has just recently achieved such a speed, while preserving all the same 3-D high-fidelity physics in the simulation mathematics! In addition, the radically new system will be ported to a High Performance Computing (HPC) center with several thousand processors so that it is realistic to expect that these high-fidelity simulations will soon be performed at a speed of only a few seconds per tem- plate, or thousands of templates per day. The future of this work, and its value to the U. S. Navy mission, looks very ex- citing indeed.
Acknowledgments
The author extends his sincere appreciation to Drs. Kwang Lee and Gary Sammelmann at NSWC PCD: Kwang for building and executing PC-ACOLOR simulations and Gary for his systems and mathematics support. The Office of Na- val Research has sponsored the development of the PC-AC- OLOR simulation system since its inception.
Biosketch
Dave Burnett is the U.S. Na- vy’s Senior Technologist for Computational Structural Acoustics. He holds 25 U.S. and international patents in the fields of computational acoustics and electromagne- tism and is the author of two books on finite element analy-
sis. Springer/ASA Press recently approved his writing a new book on computational structural acoustics. He is a Fellow of Bell Labs (formerly the R&D division of AT&T) and of the Acoustical Society, an associate editor for JASA, and an editor for the Journal of Computational Acoustics. He holds BS, MS, and PhD degrees from Cornell, Caltech and U. C. Berkeley, respectively.
References
Burnett, D. S. (1987). Finite Element Analysis: From Concepts to Applica- tions (Addison-Wesley, Reading, MA).
Burnett, D. S. (2012). “Radiation boundary conditions for the Helmholtz equation for ellipsoidal, prolate spheroidal, oblate spheroidal and spherical domain boundaries,” Journal of Computational Acoustics 20(4), 1230001- 1 – 1230001-35.
Burnett, D. S. (2015). “Underwater Acoustic Scattering Signature,” Mc- Graw-Hill Encyclopedia of Science & Technology, 2015 Yearbook.
IACM (2014), International Association of Computational Mechanics, http://iacm.info/spacehome/1/0#.
Mindlin, R. D. (1960). Structural Mechanics (Pergamon Press, New York, NY), pp. 199-232.
Oberkampf, W. L., Trucano, T. G., and Hirsch, C. (2002). “Verification, Validation, and Predictive Capability in Computational Engineering and Physics,” Foundations for Verification and Validation in the 21st Century Workshop, Johns Hopkins Univ., Applied Physics Laboratory.
Post, D. E., and Votta, L. G. (2005). “Computational Science Demands a New Paradigm,” Physics Today, 35-41.
Williams, K. L., Kargl, S. G., Thorsos, E. I., Burnett, D. S., Lopes, J. L., Zam- polli, M. and Marston, P. L. (2010). “Acoustic scattering from a solid alumi- num cylinder in contact with a sand sediment: Measurements, modeling, and interpretation,” Journal of the Acoustical Society of America 127(6), 3356-3371.
Zemanek, J., Jr. (1972). “An experimental and theoretical investigation of elastic wave propagation in a cylinder,” Journal of the Acoustical Society of America 51(1), 265-283.
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