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We consider self-similar approximations of nonlinear hyperbolic systems in one space dimension with Riemann initial data and general diffusion matrix. We assume that the matrix of the system is strictly hyperbolic and the diffusion matrix…

Analysis of PDEs · Mathematics 2008-12-16 K. T. Joseph , Philippe G. LeFloch

In this article we address some issues related to the initial value problems for a rotating shallow water hyperbolic system of equations and the diffusive regularization of this system. For initial data close to the solution at rest, we…

Analysis of PDEs · Mathematics 2021-03-10 Nabil Bedjaoui , Vivien Desveaux , Olivier Goubet , Alice Masset

We introduce a new wave formulation for the relativistic Euler equations with vacuum boundary conditions that consists of a system of non-linear wave equations in divergence form with a combination of acoustic and Dirichlet boundary…

General Relativity and Quantum Cosmology · Physics 2019-07-23 Todd A. Oliynyk

We derive the soliton matrices corresponding to an arbitrary number of higher-order normal zeros for the matrix Riemann-Hilbert problem of arbitrary matrix dimension, thus giving the complete solution to the problem of higher-order…

Exactly Solvable and Integrable Systems · Physics 2009-11-10 V. S. Shchesnovich , J. Yang

A collection of arbitrarily-shaped solid objects, each moving at a constant speed, can be used to mix or stir ideal fluid, and can give rise to interesting flow patterns. Assuming these systems of fluid stirrers are two-dimensional, the…

Complex Variables · Mathematics 2017-01-03 Mohamed M. S. Nasser , Christopher C. Green

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

This work presents the Riemann solution for three-phase flow in porous media under the condition that oil viscosity exceeds that of water and gas. We classify all Riemann solution problems for scenarios where the left states $L$ lie along…

Analysis of PDEs · Mathematics 2025-06-12 Luis Fernando Lozano , Furtado Frederico , De Souza Aparecido , Marchesin Dan

In a number of physically important cases, the nonholonomically (nonintegrable) constrained Ricci flows can be modelled by exact solutions of Einstein equations with nonhomogeneous (anisotropic) cosmological constants. We develop two…

Mathematical Physics · Physics 2009-02-17 Sergiu I. Vacaru

The importance of contact discontinuities in 2D isothermal flows has rarely been discussed, since most Riemann solvers are derived for 1D Euler equations. We present a new contact resolving approximate Riemann solver for the isothermal…

Computational Physics · Physics 2015-07-20 Manuel Jung , Tobias F. Illenseer , Wolfgang J. Duschl

An explicit expression for the Dirichlet-Neumann operator for surface water waves is presented. For non-overturning waves, but without assuming small amplitudes, the formula is first derived in two dimensions, subsequently extrapolated in…

Analysis of PDEs · Mathematics 2022-11-09 Didier Clamond

Overdetermined systems of first kind integral equations appear in many applications. When the right-hand side is discretized, the resulting finite-data problem is ill-posed and admits infinitely many solutions. We propose a numerical method…

Numerical Analysis · Mathematics 2023-07-26 Patricia Díaz de Alba , Luisa Fermo , Federica Pes , Giuseppe Rodriguez

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

This paper is presented to give numerical solutions of some cases of nonlinear wave-like equations with variable coefficients by using Reduced Differential Transform Method (RDTM). RDTM can be applied most of the physical, engineering,…

Numerical Analysis · Mathematics 2014-07-21 Murat Gubes , Yildiray Keskin , Galip Oturanc

The single-wave model equations are transformed to an exact hydrodynamic closure by using a class of solutions to the Vlasov equation corresponding to the waterbag model. The warm fluid dynamic equations are then manipulated by means of the…

Plasma Physics · Physics 2015-03-17 Kiril B. Marinov , Stephan I. Tzenov

We consider the problem of global in time existence and uniqueness of solutions of the 3-D infinite depth full water wave problem. We show that the nature of the nonlinearity of the water wave equation is essentially of cubic and higher…

Analysis of PDEs · Mathematics 2015-05-14 Sijue Wu

Two new approaches to solving first-order quasilinear elliptic systems of PDEs in many dimensions are proposed. The first method is based on an analysis of multimode solutions expressible in terms of Riemann invariants, based on links…

Mathematical Physics · Physics 2014-10-01 A. M. Grundland , V. Lamothe

In this paper the new procedure for a construction of an approximated solution to initial data problem for one-dimensional pressureless gas dynamics system is introduced. The procedure is based on solving the Riemann problems and tracking…

Analysis of PDEs · Mathematics 2020-08-04 Marko Nedeljkov , Sanja Ružičić

The paper studies inverse problems of determining unknown coefficients in various semi-linear and quasi-linear wave equations. We introduce a method to solve inverse problems for non-linear equations using interaction of three waves, that…

Analysis of PDEs · Mathematics 2023-05-10 Ali Feizmohammadi , Matti Lassas , Lauri Oksanen

We are interested in the numerical solution of large systems of hyperbolic conservation laws or systems in which the characteristic decomposition is expensive to compute. Solving such equations using finite volumes or Discontinuous Galerkin…

Numerical Analysis · Mathematics 2017-08-29 Birte Schmidtmann , Manuel Torrilhon

An important challenge when coupling two different time dependent problems is to increase parallelization in time. We suggest a multirate Neumann-Neumann waveform relaxation algorithm to solve two heterogeneous coupled heat equations. In…

Numerical Analysis · Mathematics 2018-05-14 Azahar Monge , Philipp Birken