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Potential-based formulation with generalized Lorenz gauge can be used in the quantization of electromagnetic fields in inhomogeneous media. However, one often faces the redundancy of modes when finding eigenmodes from potential-based…

Optics · Physics 2023-01-10 Jie Zhu , Thomas E. Roth , Dong-Yeop Na , Weng Cho Chew

We present an energy conserving lattice Boltzmann model based on a crystallographic lattice for simulation of weakly compressible flows. The theoretical requirements and the methodology to construct such a model are discussed. We…

Computational Physics · Physics 2020-01-29 Praveen Kumar Kolluru , Mohammad Atif , Manjusha Namburi , Santosh Ansumali

Absorbing layers are sometimes required to be impractically thick in order to offer an accurate approximation of an absorbing boundary condition for the Helmholtz equation in a heterogeneous medium. It is always possible to reduce an…

Numerical Analysis · Mathematics 2014-08-15 Rosalie Bélanger-Rioux

We investigate the sound propagation in an air-filled tube periodically loaded with Helmholtz resonators. By tuning the Helmholtz with the Bragg resonance, we study the efficiency of slow sound propagation in the presence of the intrinsic…

Materials Science · Physics 2015-06-18 G. Theocharis , O. Richoux , V. Romero-García , V. Tournat

Acoustic models of resonant duct systems with turbulent flow depend on fitted constants based on expensive experimental test series. We introduce a new model of a resonant cavity, flush mounted in a duct or flat plate, under grazing…

Fluid Dynamics · Physics 2019-06-04 Lewin Stein , Joern Sesterhenn

A modified HLLC-type contact preserving Riemann solver for incompressible two-phase flows using the artificial compressibility formulation is presented. Here, the density is omitted from the pressure evolution equation. Also, while…

Computational Physics · Physics 2022-07-14 Sourabh P. Bhat , J. C. Mandal

Flows in which the primary features of interest do not rely on high-frequency acoustic effects, but in which long-wavelength acoustics play a nontrivial role, present a computational challenge. Integrating the entire domain with…

Numerical Analysis · Mathematics 2018-08-09 Emmanuel Motheau , Max Duarte , Ann Almgren , John B. Bell

We propose a scheme of acoustic spherical cloaking by means of background irrotational flow in compressible fluid. The background flow forms a virtual curved spacetime and guides the sound waves bypass the cloaked objects. To satisfy the…

Classical Physics · Physics 2016-08-24 Ruo-Yang Zhang , Qing Zhao , Mo-Lin Ge

In this paper, the compressible Euler system with velocity alignment and damping is considered, where the influence matrix of velocity alignment is not positive definite. Sound speed is used to reformulate the system into symmetric…

Analysis of PDEs · Mathematics 2019-12-04 Lining Tong , Li Chen , Simone Göttlich , Shu Wang

The present study reports the effect of different source terms on the near and far-field acoustic characteristics of compressible flow over a rectangular cavity using hybrid computational aeroacoustics methodology. We use a low dispersive…

Fluid Dynamics · Physics 2021-05-19 Nitish Arya , Ashoke De

We propose a number of variational regularisation methods for the estimation and decomposition of motion fields on the $2$-sphere. While motion estimation is based on the optical flow equation, the presented decomposition models are…

Optimization and Control · Mathematics 2014-03-05 Clemens Kirisits , Lukas F. Lang , Otmar Scherzer

The displacement field for three dimensional dynamic elasticity problems in the frequency domain can be decomposed into a sum of a longitudinal and a transversal part known as a Helmholtz decomposition. The Cartesian components of both the…

Computational Physics · Physics 2019-10-02 Evert Klaseboer , Qiang Sun , Derek Y. C. Chan

Implicit solvers for atmospheric models are often accelerated via the solution of a preconditioned system. For block preconditioners this typically involves the factorisation of the (approximate) Jacobian resulting from linearization of the…

Numerical Analysis · Mathematics 2024-10-03 David Lee , Alberto F. Martín , Kieran Ricardo

We present a reduced basis approach to solve the convected Helmholtz equation with several physical parameters. Physical parameters characterize the aeroacoustic wave propagation in terms of the wave and Mach numbers. We compute solutions…

Numerical Analysis · Mathematics 2015-06-10 Myoungnyoun Kim , Imbo Sim

Absorbing layers are sometimes required to be impractically thick in order to offer an accurate approximation of an absorbing boundary condition for the Helmholtz equation in a heterogeneous medium. It is always possible to reduce an…

Numerical Analysis · Mathematics 2014-01-20 Rosalie Bélanger-Rioux , Laurent Demanet

In this paper we present an overview of recent progress on the development and analysis of domain decomposition preconditioners for discretised Helmholtz problems, where the preconditioner is constructed from the corresponding problem with…

Numerical Analysis · Mathematics 2016-06-24 I. G. Graham , E. A. Spence , E. Vainikko

In this paper we proceed with investigation of connections between Fokker - Planck equation and continuum mechanics. In spectral decomposition of Fokker - Planck equation solution we preserve only terms with the smallest degree of damping.…

Chaotic Dynamics · Physics 2007-09-17 Igor A. Tanski

We introduce a novel multi-resolution Localized Orthogonal Decomposition (LOD) for time-harmonic acoustic scattering problems that can be modeled by the Helmholtz equation. The method merges the concepts of LOD and operator-adapted wavelets…

Numerical Analysis · Mathematics 2022-11-24 Moritz Hauck , Daniel Peterseim

We consider the Cauchy problem for incompressible viscoelastic fluids in the whole space $\mathbb{R}^d$ ($d=2,3$). By introducing a new decomposition via Helmholtz's projections, we first provide an alternative proof on the existence of…

Analysis of PDEs · Mathematics 2023-07-28 Xianpeng Hu , Hao Wu

We consider the wave equation for sound in a moving fluid with a fourth-order anomalous dispersion relation. The velocity of the fluid is a linear function of position, giving two points in the flow where the fluid velocity matches the…

General Relativity and Quantum Cosmology · Physics 2016-09-29 T. G. Philbin