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A representation of solutions of the wave equation with two spatial coordinates in terms of localized elementary ones is presented. Elementary solutions are constructed from four solutions with the help of transformations of the affine…

Mathematical Physics · Physics 2015-06-05 Maria V. Perel , Evgeny A. Gorodnitskiy

Excitation of waves in a three-layer acoustic wavegide is studied. The wave field is presented as a sum of integrals. The summation is held over all waveguide modes. The integration is performed over the temporal frequency axis. The…

Analysis of PDEs · Mathematics 2017-04-04 A. V. Shanin , K. S. Knyazeva

We develop a variational calculus for entropy solutions of the Generalized Riemann Problem (GRP) for strictly hyperbolic systems of conservation laws where the control is the initial state. The GRP has a discontinuous initial state with…

Optimization and Control · Mathematics 2025-09-29 Jannik Breitkopf , Stefan Ulbrich

We revisit the problem of solving the one-dimensional wave equation on a domain with moving boundary. In J. Math. Phys. 11, 2679 (1970), Moore introduced an interesting method to do so. As only in rare cases, a closed analytical solution is…

Numerical Analysis · Mathematics 2025-05-27 Michiel Lassuyt , Emma Vancayseele , Wouter Deleersnyder , David Dudal , Sebbe Stouten , Koen Van Den Abeele

We study the wave equation in a bounded domain or on a compact Riemannian manifold with boundary. Assume that we are given the hyperbolic Neumann-to-Dirichlet map on the boundary corresponding to physical boundary measurements. We consider…

Analysis of PDEs · Mathematics 2007-08-17 Matias Dahl , Anna Kirpichnikova , Matti Lassas

In an influential 1964 article, P. Lax studied $2 \times 2$ genuinely nonlinear strictly hyperbolic PDE systems (in one spatial dimension). Using the method of Riemann invariants, he showed that a large set of smooth initial data lead to…

Analysis of PDEs · Mathematics 2017-07-18 Jared Speck , Gustav Holzegel , Jonathan Luk , Willie Wong

We deal with two dynamical systems associated with a Riemannian manifold with boundary. The first one is a system governed by the scalar wave equation, the second is governed by the Maxwell equations. Both of the systems are controlled from…

Mathematical Physics · Physics 2015-06-19 M. I. Belishev , M. N. Demchenko

We study the stability of composite waves consisting of a shock profile and a rarefaction wave for the one-dimensional isothermal Navier--Stokes--Poisson (NSP) system, which describes the ion dynamics in a collision-dominated plasma. More…

Analysis of PDEs · Mathematics 2025-08-15 Wanyong Shim

We study the initial value problem for the wave maps defined on the cyclic spacetime with the target Riemannian manifold that is responsive (see definition of the self coherence structure) to the parametric resonance phenomena. In…

Analysis of PDEs · Mathematics 2020-03-30 Karen Yagdjian , Anahit Galstian , Nathalie M. Luna-Rivera

Oceanic waves registered by satellite observations often have curvilinear fronts and propagate over various currents. In this paper, we study long linear and weakly-nonlinear ring waves in a stratified fluid in the presence of a…

Fluid Dynamics · Physics 2016-04-12 K. R. Khusnutdinova , X. Zhang

Scalar wave scattering by many small particles of arbitrary shapes with impedance boundary condition is studied. The problem is solved asymptotically and numerically under the assumptions a << d << lambda, where k = 2pi/lambda is the wave…

Numerical Analysis · Mathematics 2016-02-16 Alexander Ramm , Nhan Tran

We study biminimal immersions, that is immersions which are critical points of the bienergy for normal variations with fixed energy. We give a geometrical description of the Euler-Lagrange equation associated to biminimal immersions for: i)…

Differential Geometry · Mathematics 2007-05-23 E. Loubeau , S. Montaldo

In this article, we investigate the two-dimensional pressureless Euler equations with three constant Riemann initial data. Our primary focus is on the wave interactions involving contact discontinuities and delta shocks. A distinguishing…

Analysis of PDEs · Mathematics 2025-07-24 Anamika Pandey , T. Raja Sekhar

This paper proposes an original Riemmanian geometry for low-rank structured elliptical models, i.e., when samples are elliptically distributed with a covariance matrix that has a low-rank plus identity structure. The considered geometry is…

Differential Geometry · Mathematics 2020-01-07 Florent Bouchard , Arnaud Breloy , Guillaume Ginolhac , Alexandre Renaux , Frédéric Pascal

Exact solutions of the linear water-wave problem describing oblique waves over a submerged horizontal cylinder of small (but otherwise fairly arbitrary) cross-section in a two-layer fluid are constructed in the form of convergent series in…

Mathematical Physics · Physics 2021-07-08 P. Zhevandrov , A. Merzon , M. I. Romero Rodríguez , J. E. De la Paz Méndez

Corrugation instabilities occurring for solutions of the Riemann problem in relativistic hydrodynamics in which the fluid moves with a non-zero velocity tangent to the initial discontinuity are studied numerically. We perform simulations…

Mathematical Physics · Physics 2015-05-27 Patryk Mach

We study long surface and internal ring waves propagating in a stratified fluid over a parallel shear flow. The far-field modal and amplitude equations for the ring waves are presented in dimensional form. We re-derive them from the…

Fluid Dynamics · Physics 2021-09-30 Curtis Hooper , Karima Khusnutdinova , Roger Grimshaw

We discuss the procedure for the exact solution of the Riemann problem in special relativistic magnetohydrodynamics (MHD). We consider both initial states leading to a set of only three waves analogous to the ones in relativistic…

General Relativity and Quantum Cosmology · Physics 2009-11-11 B. Giacomazzo , L. Rezzolla

We consider the Riemann problem composed of two shocks for the 1D Euler system. We show that the Riemann solution with two shocks is stable and unique in the class of weak inviscid limits of solutions to the Navier-Stokes equations with…

Analysis of PDEs · Mathematics 2020-11-12 Moon-Jin Kang , Alexis Vasseur

We present a large-amplitude existence theory for two-dimensional solitary waves propagating through a two layer body of water. The domain of the fluid is bounded below by an impermeable flat ocean floor and above by a free boundary at…

Analysis of PDEs · Mathematics 2020-12-02 Daniel Sinambela