Abstract Recently, metasurfaces have been proven to be effective and compact devices for the design of arbitrary wavefronts. Metasurfaces are planar metamaterials with a subwavelength thickness that allows wavefront shaping by introducing in-plane variations, namely, gradients, in spatial wave response these flat structures. Here we report new class acoustic gradient-index (GRIN) engineered from soft graded-porous silicone rubber high index broadband ultrasonic three-dimensional water. The...

The thermal properties of a material with spatio-temporal modulation in both the conductivity and mass density are studied. special configuration studied here consists wave-like fashion. It is found that these materials behaves, an effective way, as internal convection-like term provides them non-reciprocal properties, sense flow heat has different when it propagates same direction or opposite one to parameters. An medium description presented which accurately describes modulated material,...

A method to derive homogeneous effective constitutive equations for periodically layered elastic media is proposed. The crucial and novel idea underlying the procedure that coefficients of dynamic medium can be associated with matrix logarithm propagator over a unit period. are shown have structure Willis material, characterized by anisotropic inertia coupling between momentum strain, in addition constants. Expressions presented material parameters which formally valid at any frequency...

One-dimensional propagation of a longitudinal wave through an infinite piezoelectric periodically layered structure is considered. The unit cell consists, in general, multilayers separated by thin electrodes which are connected capacitor with capacity Cj that plays the role external electric control providing tunability mechanical properties. main focus present study on effective properties characterizing homogenized medium. Due to boundary conditions, 4×4 transfer matrix M period T can be...

We report the achievement of highly monodisperse emulsions exhibiting about ten acoustic Mie resonances. Thanks to robotics, effective properties such strongly scattering media can be precisely targeted by means production calibrated (random) liquid-droplets. Ultrasonic experiments are compared, with an excellent quantitative agreement, theoretical predictions derived within framework independent approximation. The dependence sound speed and attenuation on both size volume fraction droplets...

We present a homogenization method for periodic acoustic composites based on the Plane Wave Expansion (PWE) method. show that description of needs constitutive parameters which depend frequency and wavenumber, meaning effective material is resonant nonlocal. Also, an anisotropic mass density additional parameter, called Willis term in analogy to its counterpart elasticity, are found. Numerical calculations compare with traditional multiple scattering method, showing good agreement between...

The paper is concerned with the propagation of shear horizontal surface waves (SHSW) in semi-infinite elastic media vertically periodic continuous and/or discrete variation material properties. existence and spectral properties SHSW are shown to be intimately related shape profile. Generally, dispersion branches represent randomly broken intervals on ( ω , k ) plane. They may, however, display a particular regularity being confined certain distinct ranges slowness s = / which can predicted...

We identify an acoustic process in which the conversion of angular momentum between its spin and orbital form takes place. The interaction evanescent wave propagating at interface two immiscible fluids isolated droplet is considered. elliptical motion fluid supporting incident associated with a simple state momentum, quantity recently introduced for waves literature. experimentally observe that this field predominantly forces directional transport circling droplet's interior, revealing...

In this work, we describe the preparation of emulsions fluorinated ferrofluid droplets suspended in a yield-stress hydrogel (Bingham fluid) with potential applications for ultrasound (US) spectroscopy and imaging. Fluorinated ferrofluids were obtained using an original multi-step process leading to appropriate suspension magnetic nanoparticles (MNPs) coated by layer fluoroalkylsilane oil. The efficiency sol–gel coating reaction was assessed several methods including infrared X-ray...

The influence of size polydispersity on the resonant acoustic properties dilute emulsions, made fluorinated-oil droplets, is quantitatively investigated. Ultrasound attenuation and dispersion measurements various samples with controlled polydispersities, ranging from 1% to 13%, are found be in excellent agreement predictions based independent scattering approximation. By relating particle-size distribution synthesized emulsions quality factor predicted multipolar resonances, number...

An original approach is proposed here to reversibly tune Mie scattering resonances occurring in random media by means of external low induction magnetic fields. This valid for both electromagnetic and acoustic waves. The experimental demonstration supported ultrasound experiments performed on emulsions made fluorinated ferrofluid spherical droplets dispersed a Bingham fluid. We show that the electromagnet-induced change droplet shape into prolate spheroids, with moderate aspect ratio 2.5,...

We report a quasi-flat and sub-wavelength acoustic lens built using soft matter process for broadband ultrasonic 3D focusing in water. By simple emulsion templating method, porous material with high index relative to water (∼5) has been molded shaped into convergent very low curvature thickness smaller than the working wavelength This kind of metasurface generates narrow focused beam, its focal length can be adjusted. These lenses may great interest underwater applications, where imaging are...

This paper presents a theoretical investigation of the generation Lamb waves inside an immersed plate by complex harmonic inhomogeneous plane waves. Whereas free modes fluid-loaded are classically assumed to be formed with real frequency (leaky waves), nature is searched in this study terms combinations transient characterized slowness vector and frequency. It shown that dispersion curves (only complex) can very different from permanent leaky complex), especially for A0 S0 which there exists...

Propagation of electromagnetic and acoustic plane waves in dissipative isotropic homogeneous media is described terms the Poynting vector complex-valued wave vector. The negative sign refractive index, which explained by presence backward bulk waves, then directly related to phase angle wavenumber. Attention focused on an alternative description dealing with dynamic material parameters: relative permittivity ϵ permeability μ for motion, modulus κ mass density ρ motion. 2D spaces parameters...