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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 addresses the problems of spline interpolation on smooth Riemannian manifolds, with or without the inclusion of least-squares fitting. Our unified approach utilizes gradient flows for successively connected curves or networks,…

Optimization and Control · Mathematics 2025-10-29 Chun-Chi Lin , Dung The Tran

We study the global existence of a unique strong solution and its large-time behavior of a two-phase fluid system consisting of the compressible isothermal Euler equations coupled with compressible isentropic Navier-Stokes equations through…

Analysis of PDEs · Mathematics 2016-07-04 Young-Pil Choi

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

We find an explicit form of entropy solutions to a Riemann problem for a degenerate nonlinear parabolic equation with piecewise constant velocity and diffusion coefficients. It is demonstrated that this solution corresponds to the minimum…

Analysis of PDEs · Mathematics 2023-02-01 Evgeny Yu. Panov

Let $B_1$ be the unit open disk in $\Real^2$ and $M$ be a closed Riemannian manifold. In this note, we first prove the uniqueness for weak solutions of the harmonic map heat flow in $H^1([0,T]\times B_1,M)$ whose energy is non-increasing in…

Differential Geometry · Mathematics 2010-10-19 Lu Wang

In this paper, we discuss initial-boundary value problems for linear diffusion equation with multiple time-fractional derivatives. By means of the Mittag-Leffler function and the eigenfunction expansion, we reduce the problem to an integral…

Analysis of PDEs · Mathematics 2013-11-12 Zhiyuan Li , Masahiro Yamamoto

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

We introduce a new approach to prove the global existence and uniqueness of suitable weak solutions of the heat flow of harmonic mappings into CAT(0) metric spaces. Our method allows also to prove Lipschitz continuity in spatial variables…

Analysis of PDEs · Mathematics 2026-04-07 Fang-Hua Lin , Antonio Segatti , Yannick Sire , Changyou Wang

We have generalised the exact solution of the Riemann problem in special relativistic hydrodynamics for arbitrary tangential flow velocities. The solution is obtained by solving the jump conditions across shocks plus an ordinary…

Astrophysics · Physics 2007-05-23 J. Pons , J. Ma. Marti , E. Muller

Riemann problems at geometric discontinuities are a classic and fascinating issue of hydraulics. In the present paper, the complete solution to the Riemann problem of the one-dimensional Shallow water Equations at monotonic width…

Fluid Dynamics · Physics 2021-08-18 Giada Varra , Veronica Pepe , Luigi Cimorelli , Renata Della Morte , Luca Cozzolino

We consider fixed points of steady solutions and flow directions using the boson Boltzmann equation that is a one-dimensionally reduced kinetic equation after the angular integration. With an elastic collision integral of the two-to-two…

High Energy Physics - Phenomenology · Physics 2017-10-11 Kenji Fukushima , Koichi Murase , Shi Pu

In this paper, we are concerned with the long time behavior of the piecewise smooth solutions to the generalized Riemann problem governed by the compressible isothermal Euler equations in two and three dimensions. Non-existence result is…

Analysis of PDEs · Mathematics 2018-07-23 Ning-An Lai , Wei Xiang , Yi Zhou

We consider a two-dimensional, two-layer, incompressible, steady flow, with vorticity which is constant in each layer, in an infinite channel with rigid walls. The velocity is continuous across the interface, there is no surface tension or…

Analysis of PDEs · Mathematics 2023-10-18 Karsten Matthies , Jonathan Sewell , Miles H. Wheeler

In this work, we consider a nonlocal Fisher-KPP reaction-diffusion problem with Neumann boundary condition and nonnegative initial data in a bounded domain in $\mathbb{R}^n (n \ge 1)$, with reaction term $u^\alpha(1-m(t))$, where $m(t)$ is…

Analysis of PDEs · Mathematics 2015-08-04 Shen Bian , Li Chen , Evangelos A. Latos

We investigate a one dimensional flow described with the non-compressible coupled Euler and non-compressible Navier-Stokes equations in Cartesian coordinate systems. We couple the two fluids through the continuity equation where different…

Fluid Dynamics · Physics 2021-09-28 I. F. Barna , Mátyás László

In this article the unique solution of the Cauchy problem is founded by the Riemann method. Some relations for given here confluent hypergeometric functions of two and three variables are used.

Analysis of PDEs · Mathematics 2018-03-06 Tuhtasin Ergashev

The unsteady response of nozzles with steady heat transfer forced by acoustic and/or entropy waves is modelled. The approach is based on the quasi-one-dimensional linearised Euler equations. The equations are cast in terms of three…

Fluid Dynamics · Physics 2022-03-02 Saikumar R. Yeddula , Juan Guzmán-Iñigo , Aimee S. Morgans

In this paper, a second-order generalized Riemann problem (GRP) solver is developed for a two-layer thin film model. Extending the first-order Godunov approach, the solver is used to construct a temporal-spatial coupled second-order…

Numerical Analysis · Mathematics 2025-05-27 Rahul Barthwal , Christian Rohde , Yue Wang

We consider the complete Euler system describing the time evolution of an inviscid non-isothermal gas. We show that the rarefaction wave solutions of the 1D Riemann problem are stable, in particular unique, in the class of all bounded weak…

Analysis of PDEs · Mathematics 2014-12-08 Eduard Feireisl , Ondřej Kreml , Alexis Vasseur