Anisotropic acoustic metafluid for underwater operation

Area of Science:

• Acoustics
• Materials Science
• Fluid Dynamics

Background:

• Acoustic metamaterials offer unique wave manipulation properties.
• Operating acoustic metamaterials in dense fluids like water presents significant challenges.
• Transformation acoustics aims to control wave propagation, but its application in dense fluids is limited.

Purpose of the Study:

• To present a method for designing and characterizing mechanically robust solid acoustic metamaterials (metafluids) for dense fluid operation.
• To demonstrate the fluid-like acoustic behavior of these metafluids, characterized by anisotropic mass densities and isotropic bulk modulus.
• To advance the practical application of transformation acoustics in dense fluid environments.

Main Methods:

• Design and experimental characterization of a metafluid composed of perforated steel plates and magnetic spacers.
• Utilizing rubber-coated magnetic spacers to effectively reduce the structure's shear modulus.
• Minimizing the coupling between shear and pressure waves within the solid effective medium.

Main Results:

• The developed metafluid exhibits mechanically robust properties suitable for dense fluids.
• The metafluid demonstrates fluid-like acoustic behavior with anisotropic mass densities and isotropic bulk modulus.
• The method effectively reduces shear modulus, minimizing wave coupling and enabling inertial anisotropy.

Conclusions:

• The presented method facilitates the design of solid acoustic metamaterials for dense fluid applications.
• The characterized metafluids exhibit key properties for realizing transformation acoustics in water.
• This work brings the concept of transformation acoustics in dense fluids closer to practical realization.