scholarly journals The Mixing of Polarizations in the Acoustic Excitations of Disordered Media With Local Isotropy

2018 ◽  
Vol 6 ◽  
Author(s):  
Maria G. Izzo ◽  
Giancarlo Ruocco ◽  
Stefano Cazzato
Keyword(s):  
Disordered Media ◽  
Local Isotropy ◽  
Acoustic Excitations

LBE Flows in Disordered Media

2018 ◽  
Author(s):  
Sauro Succi
Keyword(s):  
Porous Media ◽  
Fluid Mechanics ◽  
Condensed Matter ◽  
Disordered Media ◽  
Environmental Sciences ◽  
Science And Engineering ◽  
Particle Trajectories ◽  
Irregular Geometries ◽  
Numerical Tool ◽  
Bounce Back

The study of transport phenomena in disordered media is a subject of wide interdisciplinary concern, with many applications in fluid mechanics, condensed matter, life and environmental sciences as well. Flows through grossly irregular (porous) media is a specific fluid mechanical application of great practical value in applied science and engineering. It is arguably also one of the applications of choice of the LBE methods. The dual field–particle character of LBE shines brightly here: the particle-like nature of LBE (populations move along straight particle trajectories) permits a transparent treatment of grossly irregular geometries in terms of elementary mechanical events, such as mirror and bounce-back reflections. These assets were quickly recognized by researchers in the field, and still make of LBE (and eventually LGCA) an excellent numerical tool for flows in porous media, as it shall be discussed in this Chapter.

scholarly journals Anomalous Anderson localization behavior in gain-loss balanced non-Hermitian systems

Nanophotonics ◽  
2020 ◽  
Vol 10 (1) ◽  
pp. 443-452
Author(s):  
Tianshu Jiang ◽  
Anan Fang ◽  
Zhao-Qing Zhang ◽  
Che Ting Chan
Keyword(s):  
Wave Propagation ◽  
Electromagnetic Waves ◽  
Anderson Localization ◽  
Random Media ◽  
Normal Incidence ◽  
Disordered Media ◽  
One Dimensional ◽  
Gain Loss ◽  
The Waves ◽  
Localization Behavior

AbstractIt has been shown recently that the backscattering of wave propagation in one-dimensional disordered media can be entirely suppressed for normal incidence by adding sample-specific gain and loss components to the medium. Here, we study the Anderson localization behaviors of electromagnetic waves in such gain-loss balanced random non-Hermitian systems when the waves are obliquely incident on the random media. We also study the case of normal incidence when the sample-specific gain-loss profile is slightly altered so that the Anderson localization occurs. Our results show that the Anderson localization in the non-Hermitian system behaves differently from random Hermitian systems in which the backscattering is suppressed.

scholarly journals Thermal acoustic excitations with atomic-scale wavelengths in amorphous silicon

2019 ◽  
Vol 3 (6) ◽  
Author(s):  
Jaeyun Moon ◽  
Raphaël P. Hermann ◽  
Michael E. Manley ◽  
Ahmet Alatas ◽  
Ayman H. Said ◽  
...  
Keyword(s):  
Amorphous Silicon ◽  
Atomic Scale ◽  
Acoustic Excitations

scholarly journals Topological Metric Detects Hidden Order in Disordered Media

2021 ◽  
Vol 126 (4) ◽  
Author(s):  
Dominic J. Skinner ◽  
Boya Song ◽  
Hannah Jeckel ◽  
Eric Jelli ◽  
Knut Drescher ◽  
...  
Keyword(s):  
Disordered Media ◽  
Hidden Order

Impingement Cooling Flow and Heat Transfer Under Acoustic Excitations

1997 ◽  
Vol 119 (4) ◽  
pp. 810-817 ◽  
Author(s):  
C. Gau ◽  
W. Y. Sheu ◽  
C. H. Shen
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Shear Layer ◽  
Turbulence Intensity ◽  
Pressure Level ◽  
Unstable Wave ◽  
Impingement Cooling ◽  
Cooling Flow ◽  
Acoustic Excitations ◽  
Excitation Pressure

Experiments are performed to study (a) slot air jet impingement cooling flow and (b) the heat transfer under acoustic excitations. Both flow visualization and spectral energy evolution measurements along the shear layer are made. The acoustic excitation at either inherent or noninherent frequencies can make the upstream shift for both the most unstable waves and the resulting vortex formation and its subsequent pairing processes. At inherent frequencies the most unstable wave can be amplified, which increases the turbulence intensity in both the shear layer and the core and enhances the heat transfer. Both the turbulence intensity and the heat transfer increase with increasing excitation pressure levels Spl until partial breakdown of the vortex occurs. At noninherent frequencies, however, the most unstable wave can be suppressed, which reduces the turbulence intensity and decreases the heat transfer. Both the turbulence intensity and the heat transfer decreases with increasing Spl, but increases with increasing Spl when the excitation frequency becomes dominant. For excitation at high Reynolds number with either inherent or noninherent frequency, a greater excitation pressure level is needed to cause the enhancement or the reduction in heat transfer. During the experiments, the inherent frequencies selected for excitation are Fo/2 and Fo/4, the noninherent frequencies are 0.71 Fo, 0.75 Fo, and 0.8 Fo, the acoustic pressure level varies from 70 dB to 100 dB, and the Reynolds number varies from 5500 to 22,000.

Structural evolution and acoustic phonon behavior in crystalline PTFE latex films

2003 ◽  
Vol 779 ◽  
Author(s):  
M. Pierno ◽  
C.S. Casari ◽  
A. Li Bassi ◽  
M.G. Beghi ◽  
R. Piazza ◽  
...  
Keyword(s):  
Structural Evolution ◽  
Crystalline Polymer ◽  
Model Systems ◽  
Fibrillar Structure ◽  
Sintering Process ◽  
Latex Films ◽  
Force Microscopy ◽  
Crystalline Polymers ◽  
Atomic Force ◽  
Acoustic Excitations

AbstractThe structural evolution of polytetrafluoroethylene (PTFE) crystalline polymer latex films is studied at hundreds nanometer length scale by atomic force microscopy and Brillouin light scattering. In a controlled sintering process the transition is observed from the original particle distribution towards a ‘fibrillar’ structure of crystalline regions embedded in a disordered matrix. This transition is accompanied by a cross-over from localized acoustic excitations to propagating acoustic phonons, related to mesoscopic elastic properties. After sintering, a ‘mark’ of the original particulate structure persists, suggesting that filming of crystalline polymers may be analogous to sintering of ceramic powders. Films of crystalline polymers can thus be exploited as model systems to study the elasto-optical properties of granular and disordered media.

Numerical study of random lasing in three dimensional amplifying disordered media

2012 ◽  
Vol 285 (6) ◽  
pp. 1314-1322 ◽  
Author(s):  
Abbas Ghasempour Ardakani ◽  
Ali Reza Bahrampour ◽  
Seyed Mohammad Mahdavi ◽  
Mojtaba Golshani Gharyeh Ali
Keyword(s):  
Numerical Study ◽  
Three Dimensional ◽  
Disordered Media ◽  
Random Lasing
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