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

Frontiers in Physics

Ruocco, Giancarlo¹  Izzo, Maria G.²  Cazzato, Stefano³ 

[1] degli studi di Roma “La Sapienza”, Italy;Dipartimento di Ingegneria Informatica Automatica e Gestionale Antonio Ruberti, UniversitáIstituto Italiano di Tecnologia-Center for Life Nanoscience, Italy

关键词: mixing of polarizations;    Random media theory;    Dyson equation;    disordered systems;    glasses;    Acoustic excitations;   

DOI  :  10.3389/fphy.2018.00108

学科分类：物理（综合）

来源: Frontiers

【 摘 要 】

An approximate solution of the Dyson equation related to a stochastic Helmholtz equation, which describes the acoustic dynamics of a three-dimensional isotropic random medium with elastic tensor fluctuating in space, is obtained in the framework of the Random Media Theory. The wavevector-dependence of the self-energy is preserved, thus allowing a description of the acoustic dynamics at wavelengths comparable with the size of heterogeneity domains. This in turn permits to quantitatively describe the mixing of longitudinal and transverse dynamics induced by the medium's elastic heterogeneity and occurring at such wavelengths. A functional analysis aimed to attest the mathematical coherence and to define the region of validity in the frequency-wavector plane of the proposed approximate solution is presented, with particular emphasis dedicated to the case of disorder characterized by an exponential decay of the covariance function.

【 授权许可】

CC BY