Related papers: Low frequency sound attenuation in a flow duct usi…
We compute the thermal conductivity and sound attenuation length of a dilute atomic Fermi gas in the framework of kinetic theory. Above the critical temperature for superfluidity, T_c, the quasi-particles are fermions, whereas below T_c,…
We investigate the propagation of surface acoustic waves (SAWs) in a layered half-space system comprising a continuous, sub-wavelength-thick layer weakly adhering to a substrate. Using finite element simulations, we demonstrate that this…
The sound propagation is usually described by a linear homogeneous wave equation, though the air flow in a duct is described by the gas dynamics equations, using a variable cross section, which corresponds to a non linear non homogneous…
Optimal impedance for each mode is an important concept in an infinitely long duct lined with uniform absorption material. However it is not valid for finite length linings. This is because that the modes in lined ducts are not…
The manipulation of sound with acoustic metamaterials is a field of intense research, where interaction via resonance is a common application despite the significant disadvantages. We propose a novel procedure for introducing well-designed…
High-fidelity lattice-Boltzmann very-large-eddy simulations are performed to describe the noise dissipation mechanisms in a single cavity acoustic liner subjected to grazing turbulent flow at a centreline Mach number of 0.3 and plane…
Future cellular systems will make use of millimeter wave (mmWave) frequency bands. Many users in these bands are located indoors, i.e., inside buildings, homes, and offices. Typical building material attenuations in these high frequency…
Fano resonance featuring asymmetric spectral profiles originates from the interference of local resonances and background continuum. Its narrow-band nature looks seemingly adverse to broadband noise cancellation purposes. In this study, we…
Total acoustic transmission between water and air is modeled using a purely solid interface comprising two elastic plates separated by periodically spaced ribs. The frequency of full transmission depends only on, and is inversely…
We investigate the acoustical properties of uncompressed and compressed open-celled aluminum metal foams fabricated using a directional solidification foaming process. We compressed the fabricated foams using a hydraulic press to different…
Sound is usually generated in a medium by an electromechanical vibrating structure. The geometrical size and inertia of the structure set the frequency cutoff in the sound-transduction mechanism and, often, different vibrating structures…
We report the experimental design of a 1D stealth acoustic material, namely a material that suppresses the acoustic scattering for a given set of incident wave vectors. The material consists of multiple scatterers, rigid diaphragms, located…
We report theoretical and experimental results for a new type of homogenized acoustic metamaterials with negative effective mass density. We constructed one-dimensional metamaterial, which is a tube with an array of very thin elastic…
Similar to their optic counterparts, acoustic components are anticipated to flexibly tailor the propagation of sound. However, the practical applications, e.g. for audible sound with large wavelengths, are frequently hampered by the issue…
By combining analytical and numerical approaches, we theoretically investigate the effect of fabrication imperfections, e.g. roughness at metal interfaces, on nanometer metal-insulator-metal waveguides supporting slow gap-plasmon modes.…
Underwater sound isolation has been a long-standing fundamental issue in industry and military fields. Starting from a simple theoretical model, here an air-sealed metasurface is proposed to overcome this problem. Comparing with the sample…
We introduce the acoustic equivalent of 'supercoupling' by studying the anomalous sound transmission and uniform energy squeezing through ultranarrow acoustic channels filled with zero-density metamaterials. We propose their realization by…
A concept of ultra-thin low frequency perfect sound absorber is proposed and demonstrated experimentally. To minimize non-linear effects, an high ratio of active area to total area is used to avoid large localized amplitudes. The absorber…
The authors present an impedance-matched reduced version of acoustic cloaking whose mass is in a reasonable range. A layered cloak design with isotropic material is also proposed for the reduced cloak. Numerical calculations from the…
The attenuation of longitudinal acoustic phonons up to frequencies nearing 250 GHz is measured in vitreous silica with a picosecond optical technique. Taking advantage of interferences on the probe beam, difficulties encountered in early…