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We introduce a novel virtual element method (VEM) for the two dimensional Helmholtz problem endowed with impedance boundary conditions. Local approximation spaces consist of Trefftz functions, i.e., functions belonging to the kernel of the…

Numerical Analysis · Mathematics 2018-10-26 L. Mascotto , I. Perugia , A. Pichler

We present Helmholtz or Helmholtz like equations for the approximation of the time-harmonic wave propagation in gases with small viscosity, which are completed with local boundary conditions on rigid walls. We derived approximative models…

Analysis of PDEs · Mathematics 2019-05-22 Kersten Schmidt , Anastasia Thöns-Zueva

We present a fast method for numerically solving the inhomogeneous Helmholtz equation. Our iterative method is based on the Born series, which we modified to achieve convergence for scattering media of arbitrary size and scattering…

Computational Physics · Physics 2016-07-14 Gerwin Osnabrugge , Saroch Leedumrongwatthanakun , Ivo M. Vellekoop

The study of Einstein equations leads naturally to Cauchy problems with initial data on hypersurfaces which closely resemble hyperboloids in Minkowski space-time, and with initial data with polyhomogeneous asymptotics, that is, with…

Analysis of PDEs · Mathematics 2007-05-23 Piotr T. Chrusciel , Szymon Leski

The paper is concerned with an inverse point source problem for the Helmholtz equation. It consists of recovering the locations and amplitudes of a finite number of radiative point sources inside a given inhomogeneous medium from the…

Analysis of PDEs · Mathematics 2021-09-01 Gang Bao , Yuantong Liu , Faouzi Triki

In this paper, we consider the scattering of a plane wave by a rigid obstacle embedded in a homogeneous and isotropic elastic medium in three dimensions. Based on the Helmholtz decomposition, the elastic scattering problem is reduced to a…

Numerical Analysis · Mathematics 2022-09-14 Heping Dong , Jun Lai , Peijun Li

A new Hardy space Hardy space approach of Dirichlet type problem based on Tikhonov regularization and Reproducing Hilbert kernel space is discussed in this paper, which turns out to be a typical extremal problem located on the upper…

Numerical Analysis · Mathematics 2017-05-31 Zhulin Liu , C. L. Philip Chen

We establish a rigidity theorem for annular sector-like domains in the setting of overdetermined elliptic problems on model Riemannian manifolds. Specifically, if such a domain admits a solution to the inhomogeneous Helmholtz equation…

Analysis of PDEs · Mathematics 2025-06-03 João Marcos do Ó , Jaqueline de Lima , Márcio Santos

We study the ``hyperboloidal Cauchy problem'' for linear and semi-linear wave equations on Minkowski space-time, with initial data in weighted Sobolev spaces allowing singular behaviour at the boundary, or with polyhomogeneous initial data.…

Analysis of PDEs · Mathematics 2007-05-23 Piotr T. Chrusciel , O. Lengard

In several geophysical applications, such as full waveform inversion and data modelling, we are facing the solution of inhomogeneous Helmholtz equation. The difficulties of solving the Helmholtz equa- tion are two fold. Firstly, in the case…

Geophysics · Physics 2017-12-27 Nasser Kazemi

High-dimensional Lagrange interpolation plays a pivotal role in finite element methods, where ensuring the unisolvence and symmetry of its interpolation space and nodes set is crucial. In this paper, we leverage group action and group…

Numerical Analysis · Mathematics 2024-05-24 Yulin Xie , Yifa Tang

We use the work of Milton, Seppecher, and Bouchitt\'{e} on variational principles for waves in lossy media to formulate a finite element method for solving the complex Helmholtz equation that is based entirely on minimization. In…

Numerical Analysis · Mathematics 2010-08-02 Russell B. Richins , David C. Dobson

A boundary integral equation method for the 3-D Helmholtz equation in multilayered media with many quasi-periodic layers is presented. Compared with conventional quasi-periodic Green's function method, the new method is robust at all…

Numerical Analysis · Mathematics 2022-11-29 Bowei Wu , Min Hyung Cho

We study a space-time finite element approach for the nonhomogeneous wave equation using a continuous time Galerkin method. We present fully implicit examples in 1+1, 2+1, and 3+1 dimensions using linear quadrilateral, hexahedral, and…

General Relativity and Quantum Cosmology · Physics 2008-11-26 Matthew Anderson , Jung-Han Kimn

We consider the scalar Helmholtz equation with variable, discontinuous coefficients, modelling transmission of acoustic waves through an anisotropic penetrable obstacle. We first prove a well-posedness result and a frequency-explicit bound…

Analysis of PDEs · Mathematics 2022-09-20 Théophile Chaumont-Frelet , Euan A. Spence

We consider the scattering of acoustic perturbations in a presence of a flow. We suppose that the space can be split into a zone where the flow is uniform and a zone where the flow is potential. In the first zone, we apply a Prandtl-Glauert…

Computational Physics · Physics 2015-05-20 Nolwenn Balin , Fabien Casenave , François Dubois , Eric Duceau , Stefan Duprey , Isabelle Terrasse

An exactly solvable one-dimensional Hubbard model with a single Anderson impurity embedded at the boundary is constructed in the framework of the quantum inverse scattering method. The model is solved exactly by the nested Bethe ansatz…

Mathematical Physics · Physics 2025-09-10 Renjie Song , Mingchen Zheng , Junpeng Cao , Yupeng Wang

This paper introduces a time-domain combined field integral equation for electromagnetic scattering by a perfect electric conductor. The new equation is obtained by leveraging the quasi-Helmholtz projectors, which separate both the unknown…

Numerical Analysis · Mathematics 2024-07-22 Van Chien Le , Pierrick Cordel , Francesco P. Andriulli , Kristof Cools

We study time-harmonic scattering by a periodic array of penetrable, high-contrast obstacles with small period, confined to a bounded Lipschitz domain. The strong contrast between the obstacles and the background induces subwavelength…

Analysis of PDEs · Mathematics 2025-10-15 Yuxin Du , Xin Fu , Wenjia Jing

We consider the time-harmonic acoustic wave scattering by a bounded {\it anisotropic inhomogeneity} embedded in an unbounded {\it anisotropic} homogeneous medium. The material parameters may have discontinuities across the interface between…

Analysis of PDEs · Mathematics 2018-12-26 Otar Chkadua , Sergey E. Mikhailov , David Natroshvili