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In this paper the relaxed micromorphic material model for anisotropic elasticity is used to describe the dynamical behavior of a band-gap metamaterial with tetragonal symmetry. Unlike other continuum models (Cauchy, Cosserat, second…

This paper presents a hybrid numerical method to solve efficiently a class of highly anisotropic elliptic problems. The anisotropy is aligned with one coordinate-axis and its strength is described by a parameter $\eps \in (0,1]$, which can…

Numerical Analysis · Mathematics 2015-11-04 Anais Crestetto , Fabrice Deluzet , Claudia Negulescu

We consider elliptic diffusion problems with a random anisotropic diffusion coefficient, where, in a notable direction given by a random vector field, the diffusion strength differs from the diffusion strength perpendicular to this notable…

Numerical Analysis · Mathematics 2018-02-13 Helmut Harbrecht , Marc Schmidlin

In this paper, we have considered a toy model of an anisotropic universe and studied the propagation of gravitational waves in such a universe. The consideration of this toy model simplifies the analysis and helps us to illustrate the…

General Relativity and Quantum Cosmology · Physics 2019-08-20 Sucheta Datta , Sarbari Guha

A major limitation of the weakly compressible approaches to simulate incompressible flows is the appearance of artificial acoustic waves that introduce a large mass conservation error and lead to spurious oscillations in the force…

Fluid Dynamics · Physics 2024-09-12 Dheeraj Raghunathan , Y. Sudhakar

The propagation of a wave in a medium is generally affected when the medium is moving with respect to the observer. Because plasma equilibria often involve plasma flows, for instance in astrophysics or in magnetic confinement nuclear fusion…

Plasma Physics · Physics 2024-07-22 Aymeric Braud , Julien Langlois , Renaud Gueroult

In Part I of this study, we obtained the ray (group) velocity gradients and Hessians with respect to the ray locations, directions and the anisotropic model parameters, at nodal points along ray trajectories, considering general anisotropic…

Geophysics · Physics 2021-12-01 Igor Ravve , Zvi Koren

We describe and evaluate a numerical solution strategy for simulating surface acoustic waves through semiconductor devices with complex geometries. This multi-physics problem is of particular relevance to the design of quantum electronic…

Computational Physics · Physics 2007-05-23 S. Rahman , H. P. Langtangen , C. H. W. Barnes

Classically, anisotropic surface wave tomography is treated as an optimisation problem where it proceeds through a linearised two-step approach. It involves the construction of 2D group or phase velocity maps for each considered period,…

Geophysics · Physics 2020-12-08 John Keith Magali

The dispersion relation is derived for the coherent waves in fluid or elastic media supporting viscous and thermal effects and containing randomly distributed spherical scatterers. The formula obtained is the generalization of Lloyd and…

Mathematical Physics · Physics 2012-02-15 Francine Luppé , Jean-Marc Conoir , Andrew N. Norris

An acoustic wave equation for pressure accounting for viscoelastic attenuation is derived from viscoelastic equations of motion. It differs significantly from the equations proposed by Szabo. Dispersion and attenuation associated with the…

Mathematical Physics · Physics 2014-04-01 Andrzej Hanyga

In this work, we investigate mathematical models for electromagnetic wave propagation in dispersive isotropic media. We emphasize the link between physical requirements and mathematical properties of the models. A particular attention is…

Analysis of PDEs · Mathematics 2017-03-16 Maxence Cassier , Patrick Joly , Maryna Kachanovska

In this article we give an extention of the L^2-theory of anisotropic singular perturbations for elliptic problems. We study a linear and some nonlinear problems involving L^p data (1<p<2). Convergences in pseudo Sobolev spaces are proved…

Analysis of PDEs · Mathematics 2016-04-15 Chokri Ogabi

Pseudo-Hermitian operators can be used in modeling electromagnetic wave propagation in stationary lossless media. We extend this method to a class of non-dispersive anisotropic media that may display loss or gain. We explore three concrete…

Quantum Physics · Physics 2015-05-18 A. Mostafazadeh , G. Scolarici

The extended boundary condition method can be used to study planewave scattering by an ellipsoid composed of an orthorhombic dielectric-magnetic material whose relative permittivity dyadic is a scalar multiple of its relative permeability…

Bi-isotropic media, which include isotropic chiral media and Tellegen media as special cases, are the most general form of linear isotropic media where the electric displacement and the magnetic induction are related to both the electric…

Optics · Physics 2016-05-04 Seulong Kim , Kihong Kim

We present equivalent conditions and asymptotic models for the diffraction problem of elastic and acoustic waves in a solid medium surrounded by a thin layer of fluid medium. Due to the thinness of the layer with respect to the wavelength,…

Numerical Analysis · Mathematics 2022-05-16 Victor Péron

Different sequences of ellipsoids are represented on the ellipticity-rotation plane. The rotation parameter is defined as the ratio of kinetic energy related to the mean tangential equatorial velocity component to kinetic energy related to…

Instrumentation and Methods for Astrophysics · Physics 2014-11-20 R. Caimmi

We study microlocally the transmission problem at the interface between an isotropic linear elastic solid and a linear inviscid fluid. We set up a system of evolution equations describing the particle displacement and velocity in the solid,…

Analysis of PDEs · Mathematics 2021-11-08 Nikolas Eptaminitakis , Plamen Stefanov

This work concerns the modeling of radiative transfer in anisotropic turbid media using diffusion theory. A theory for the relationship between microscopic scattering properties (i.e., an arbitrary differential scattering cross-section) and…

Optics · Physics 2014-08-14 Erik Alerstam