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A generalized version of the $abcd$-Boussinesq class of systems is derived to accommodate variable bottom topography in two-dimensional space. This extension allows for the conservation of suitable energy functionals in some cases and…

Fluid Dynamics · Physics 2024-06-19 Samer Israwi , Youssef Khalifeh , Dimitrios Mitsotakis

We investigate the long time behavior of solutions to a shape and topology optimization problem with respect to the time-dependent Navier--Stokes equations. The sought topology is represented by a stationary phase-field that represents a…

Optimization and Control · Mathematics 2026-05-04 Michael Hinze , Christian Kahle , John Sebastian H. Simon

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

Obtaining sharp estimates for quantities involved in a given model is an integral part of the modeling process. For dynamical systems whose orbits display a complicated, perhaps chaotic, behaviour, the aim is usually to estimate time or…

Analysis of PDEs · Mathematics 2021-08-31 Ricardo M. S. Rosa , Roger M. Temam

A posteriori upper and lower bounds are derived for the linear finite element method (FEM) for the Helmholtz equation with large wave number. It is proved rigorously that the standard residual type error estimator seriously underestimates…

Numerical Analysis · Mathematics 2021-10-25 Songyao Duan , Haijun Wu

We consider the convected Helmholtz equation with a generalized Myers boundary condition (a boundary condition of the second-order) and characterize the set of physical parameters for which the problem is weakly well-posed. The model comes…

Analysis of PDEs · Mathematics 2025-06-26 Nabil Alami , Edward Lucyszyn , Raphaél Pain Dit Hermier , Anna Rozanova-Pierrat

This is a study of the Euler equations for free surface water waves in the case of varying bathymetry, considering the problem in the shallow water scaling regime. In the case of rapidly varying periodic bottom boundaries this is a problem…

Analysis of PDEs · Mathematics 2016-01-20 Walter Craig , David Lannes , Catherine Sulem

A nonlinear Helmholtz equation (NLH) with high wave number and Sommerfeld radiation condition is approximated by the perfectly matched layer (PML) technique and then discretized by the linear finite element method (FEM).…

Numerical Analysis · Mathematics 2022-07-12 Run Jiang , Yonglin Li , Haijun Wu , Jun Zou

We study the stationary nonhomogeneous Navier--Stokes problem in a two dimensional symmetric domain with a semi-infinite outlet (for instance, either parabo-\\loidal or channel-like). Under the symmetry assumptions on the domain, boundary…

Analysis of PDEs · Mathematics 2015-05-28 M. Chipot , K. Kaulakyt , K. Pileckas , W. Xue

Numerically solving the 2D Helmholtz equation is widely known to be very difficult largely due to its highly oscillatory solution, which brings about the pollution effect. A very fine mesh size is necessary to deal with a large wavenumber…

Analysis of PDEs · Mathematics 2022-05-17 Bin Han , Michelle Michelle

In this article we deal with a class of geometric inverse problem for bottom detection by one single measurement on the free surface in water--waves. We found upper and lower bounds for the size of the region enclosed between two different…

Analysis of PDEs · Mathematics 2020-12-02 R. Lecaros , J. López-Ríos , J. H. Ortega , S. Zamorano

Extending the wavenumber-explicit analysis of [Chen & Qiu, J. Comput. Appl. Math. 309 (2017)], we analyze the $L^2$-convergence of a least squares method for the Helmholtz equation with wavenumber $k$. For domains with an analytic boundary,…

Numerical Analysis · Mathematics 2024-07-25 Maximilian Bernkopf , Jens Markus Melenk

The solution of the Helmholtz equation in optical semiclassic approximation is associated with the calculation of ray paths and matrices of variations. The transformation rules for elements of matrices on the boundaries of the waveguide are…

Mathematical Physics · Physics 2012-12-27 I. P. Smirnov

In this paper we extend analysis of the WaveHoltz iteration -- a time-domain iterative method for the solution of the Helmholtz equation. We expand the previous analysis of energy conserving problems and prove convergence of the WaveHoltz…

Numerical Analysis · Mathematics 2022-05-26 Fortino Garcia , Daniel Appelö , Olof Runborg

As mentioned by Schwartz (1974) and Cokelet (1977), it was failed to gain convergent results of limiting Stokes' waves in extremely shallow water by means of perturbation methods even with the aid of extrapolation techniques such as…

Fluid Dynamics · Physics 2018-04-06 Xiaoxu Zhong , Shijun Liao

We study 4 problems in the area of scattering of time harmonic acoustic or electromagnetic waves by unbounded rough surfaces/inhomogeneous layers. Specifically we study: i) a boundary value problem (BVP) for the Helmholtz equation, in both…

Analysis of PDEs · Mathematics 2019-04-09 Thomas Baden-Riess

We show that the properties of the lower part of the spectrum of the Helmholtz equation for an heterogeneous system in a finite region in $d$ dimensions, where the solutions to the homogeneous problems are known, can be systematically…

Mathematical Physics · Physics 2015-12-23 Paolo Amore

We study the incompressible stationary Navier-Stokes equations in the upper-half plane with homogeneous Dirichlet boundary condition and non-zero external forcing terms. Existence of weak solutions is proved under a suitable condition on…

Analysis of PDEs · Mathematics 2023-06-02 Adrian D. Calderon , Van Le , Tuoc Phan

Formulas are derived for solutions of many-body wave scattering problems by small particles in the case of acoustically soft, hard, and impedance particles embedded in an inhomogeneous medium. The case of transmission (interface) boundary…

Mathematical Physics · Physics 2012-09-03 A. G. Ramm

We introduce and analyze a virtual element method (VEM) for the Helmholtz problem with approximating spaces made of products of low order VEM functions and plane waves. We restrict ourselves to the 2D Helmholtz equation with impedance…

Numerical Analysis · Mathematics 2015-05-20 Ilaria Perugia , Paola Pietra , Alessandro Russo