Acoustic cloaking transformations from attainable material properties
Abstract
We propose a general methodology and a set of practical recipes for the construction
of ultra-broadband acoustic cloaks-structures that can render themselves and a concealed
object undetectable by means of acoustic scattering. The acoustic cloaks presented
here are designed and function analogously to electromagnetic cloaks. However, acoustic
cloaks in a fluid medium do not suffer the bandwidth limitations imposed on their
electromagnetic counterparts by the finite speed of light in vacuum. In the absence
of specific metamaterials having arbitrary combinations of quasi-static speed of sound
and mass density, we explore the flexibility of continuum transformations that produce
approximate cloaking solutions. We show that an imperfect, eikonal acoustic cloak
(that is, one which is not impedance matched but is valid in the geometrical optics
regime) with negligible dispersion can be designed using a simple layered geometry.
Since a practical cloaking device will probably be composed of combinations of solid
materials rather than fluids, it is necessary to consider the full elastic properties
of such media, which support shear waves in addition to the compression waves associated
with the acoustic regime. We perform a systematic theoretical and numerical investigation
of the role of shear waves in elastic cloaking devices. We find that for elastic metamaterials
with Poisson's ratio v > 0.49, shear waves do not alter the cloaking effect. Such
metamaterials can be built from nearly incompressible rubbers (with v ≈ 0.499) and
fluids. We expect this finding to have applications in other acoustic devices based
on the form-invariance of the scalar acoustic wave equation. © IOP Publishing Ltd
and Deutsche Physikalische Gesellschaft.
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Journal articlePermalink
https://hdl.handle.net/10161/5078Published Version (Please cite this version)
10.1088/1367-2630/12/7/073014Publication Info
Urzhumov, Y; Ghezzo, F; Hunt, J; & Smith, DR (2010). Acoustic cloaking transformations from attainable material properties. New Journal of Physics, 12. pp. 1-21. 10.1088/1367-2630/12/7/073014. Retrieved from https://hdl.handle.net/10161/5078.This is constructed from limited available data and may be imprecise. To cite this
article, please review & use the official citation provided by the journal.
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David R. Smith
James B. Duke Distinguished Professor of Electrical and Computer Engineering
Dr. David R. Smith is currently the James B. Duke Professor of Electrical and Computer
Engineering Department at Duke University. He is also Director of the Center for Metamaterials
and Integrated Plasmonics at Duke and holds the positions of Adjunct Associate Professor
in the Physics Department at the University of California, San Diego, and Visiting
Professor of Physics at Imperial College, London. Dr. Smith received his Ph.D. in
1994 in Physics from the University of California, San D
Yaroslav A. Urzhumov
Adjunct Assistant Professor in the Department of Electrical and Computer Engineering
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<![endif]-->Dr. Urzhumov is Adjunct Assistant Professor of ECE at Duke University,
and also a Technologist at the Metamaterials Commercialization Center of Intellectual
Ventures. Previously a research faculty at Duke, he works on applied and theoretical
aspects of metama
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