One path to acoustic cloaking
Steven A. Cummer,David Schurig +1 more
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TLDR
In this paper, it was shown that the acoustic equations in a fluid are identical in form to the single polarization Maxwell equations via a variable exchange that also preserves boundary conditions, and the existence of transformation-type solutions for the 2D acoustic equations with anisotropic mass via time harmonic simulations of acoustic cloaking.Abstract:
A complete analysis of coordinate transformations in elastic media by Milton et al has shown that, in general, the equations of motion are not form invariant and thus do not admit transformation-type solutions of the type discovered by Pendry et al for electromagnetics. However, in a two-dimensional (2D) geometry, the acoustic equations in a fluid are identical in form to the single polarization Maxwell equations via a variable exchange that also preserves boundary conditions. We confirm the existence of transformation-type solutions for the 2D acoustic equations with anisotropic mass via time harmonic simulations of acoustic cloaking. We discuss the possibilities of experimentally demonstrating acoustic cloaking and analyse why this special equivalence of acoustics and electromagnetics occurs only in 2D.read more
Citations
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Elastodynamic cloaking and field enhancement for soft spheres
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Theoretical and Numerical Modeling of Acoustic Metamaterials for Aeroacoustic Applications
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A Volumetric Approach to Wake Reduction: Design, Optimization, and Experimental Verification
TL;DR: In this article, a volumetric approach is proposed to control the wake in a stationary flow past cylindrical and spherical objects, coupled with rigid, fluid-permeable structures prescribed by a macroscopic design approach.
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An experimental investigation into active structural acoustic cloaking of a flexible cylinder
TL;DR: It is shown that the practical causality constraint limits the performance of the active cloak at lower frequencies, but the causally constrained controller is able to achieve approximately 10 dB of attenuation in the far-field scattered acoustic power, using an array of 9 control actuators.
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A Unified Approach to Nonlinear Transformation Materials.
Sophia R. Sklan,Baowen Li +1 more
TL;DR: In this paper, it has been shown that nonlinearity can be incorporated into transformation optics in a consistent way, and the authors use this to illustrate a number of novel effects, including cloaking an optical soliton and modeling nonlinear solutions to Einstein's field equations.
References
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Magnetism from conductors and enhanced nonlinear phenomena
TL;DR: In this paper, it was shown that microstructures built from nonmagnetic conducting sheets exhibit an effective magnetic permeability /spl mu/sub eff/, which can be tuned to values not accessible in naturally occurring materials.
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Controlling Electromagnetic Fields
TL;DR: This work shows how electromagnetic fields can be redirected at will and proposes a design strategy that has relevance to exotic lens design and to the cloaking of objects from electromagnetic fields.
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Metamaterial Electromagnetic Cloak at Microwave Frequencies
David Schurig,Jack J. Mock,B.J. Justice,Steven A. Cummer,John B. Pendry,Anthony F. Starr,David R. Smith +6 more
TL;DR: This work describes here the first practical realization of a cloak of invisibility, constructed with the use of artificially structured metamaterials, designed for operation over a band of microwave frequencies.
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Optical Conformal Mapping
TL;DR: A general recipe for the design of media that create perfect invisibility within the accuracy of geometrical optics is developed, which can be applied to escape detection by other electromagnetic waves or sound.
Journal ArticleDOI
Ultrasonic metamaterials with negative modulus
Nicholas X. Fang,Dongjuan Xi,Jianyi Xu,Muralidhar Ambati,Werayut Srituravanich,Cheng Sun,Xiang Zhang +6 more
TL;DR: A new class of ultrasonic metamaterials consisting of an array of subwavelength Helmholtz resonators with designed acoustic inductance and capacitance with an effective dynamic modulus with negative values near the resonance frequency is reported.