title: Anisotropic acoustic metafluid for underwater operation.
abstract: The paper presents a method to design and characterize mechanically robust solid acoustic metamaterials suitable for operation in dense fluids such as water. These structures, also called metafluids, behave acoustically as inertial fluids characterized by anisotropic mass densities and isotropic bulk modulus. The method is illustrated through the design and experimental characterization of a metafluid consisting of perforated steel plates held together by rubber coated magnetic spacers. The spacers are very effective at reducing the effective shear modulus of the structure, and therefore effective at minimizing the ensuing coupling between the shear and pressure waves inside the solid effective medium. Inertial anisotropy together with fluid-like acoustic behavior are key properties that bring transformation acoustics in dense fluids closer to reality.
authors.affiliation: Department of Electrical and Computer Engineering, Duke University, Durham, North Carolina 27708, USA.
authors.forename: Bogdan-Ioan
authors.initials: BI
authors.lastname: Popa
authors.affiliation: Department of Electrical and Computer Engineering, Duke University, Durham, North Carolina 27708, USA.
authors.forename: Wenqi
authors.initials: W
authors.lastname: Wang
authors.affiliation: Department of Electrical and Computer Engineering, Duke University, Durham, North Carolina 27708, USA.
authors.forename: Adam
authors.initials: A
authors.lastname: Konneker
authors.affiliation: Department of Electrical and Computer Engineering, Duke University, Durham, North Carolina 27708, USA.
authors.forename: Steven A
authors.initials: SA
authors.lastname: Cummer
authors.affiliation: U.S. Naval Research Laboratory, Code 7160, Washington, DC 20375, USA.
authors.forename: Charles A
authors.initials: CA
authors.lastname: Rohde
authors.affiliation: U.S. Naval Research Laboratory, Code 7160, Washington, DC 20375, USA.
authors.forename: Theodore P
authors.initials: TP
authors.lastname: Martin
authors.affiliation: U.S. Naval Research Laboratory, Code 7160, Washington, DC 20375, USA.
authors.forename: Gregory J
authors.initials: GJ
authors.lastname: Orris
authors.affiliation: NRC Research Associateship Program, U.S. Naval Research Laboratory, Washington, DC 20375, USA.
authors.forename: Matthew D
authors.initials: MD
authors.lastname: Guild