When Do Riemann Solutions Consist of Rarefactions, Jumps, and Constants?

Fuente: arXiv
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Main Authors: Plohr, Bradley J., Schecter, Stephen, Marchesin, Dan
Format: Preprint
Published: 2026
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author Plohr, Bradley J.
Schecter, Stephen
Marchesin, Dan
author_facet Plohr, Bradley J.
Schecter, Stephen
Marchesin, Dan
contents A solution of a Riemann problem for a strictly hyperbolic system of conservation laws is traditionally expected to consist of rarefaction waves, jump discontinuities, and constant states. In this paper, we investigate whether a Riemann solution has this structure when the solution is only assumed to be measurable and essentially bounded. To discriminate continuous and discontinuous features in an $L^\infty$ solution, we introduce one-sided accumulation sets based on local essential images. Supposing that throughout a bounded open interval a solution is continuous in the essential image (ess-im) sense, we prove that it is a rarefaction wave if it is resonant (the characteristic speed equals $x/t$), and otherwise it is constant. Although an ess-im discontinuity might not be a jump discontinuity, we show that all ess-im accumulation states lie on a common Hugoniot locus and have the same speed. Anomalies are possible if there are limit points of ess-im discontinuities, but if the set of ess-im discontinuities is finite, then an $L^\infty$ Riemann solution has bounded variation and is composed of finitely many rarefaction waves, jump discontinuities, and constant states.
format Preprint
id arxiv_https___arxiv_org_abs_2605_21881
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle When Do Riemann Solutions Consist of Rarefactions, Jumps, and Constants?
Plohr, Bradley J.
Schecter, Stephen
Marchesin, Dan
Analysis of PDEs
35L65, 35L67
A solution of a Riemann problem for a strictly hyperbolic system of conservation laws is traditionally expected to consist of rarefaction waves, jump discontinuities, and constant states. In this paper, we investigate whether a Riemann solution has this structure when the solution is only assumed to be measurable and essentially bounded. To discriminate continuous and discontinuous features in an $L^\infty$ solution, we introduce one-sided accumulation sets based on local essential images. Supposing that throughout a bounded open interval a solution is continuous in the essential image (ess-im) sense, we prove that it is a rarefaction wave if it is resonant (the characteristic speed equals $x/t$), and otherwise it is constant. Although an ess-im discontinuity might not be a jump discontinuity, we show that all ess-im accumulation states lie on a common Hugoniot locus and have the same speed. Anomalies are possible if there are limit points of ess-im discontinuities, but if the set of ess-im discontinuities is finite, then an $L^\infty$ Riemann solution has bounded variation and is composed of finitely many rarefaction waves, jump discontinuities, and constant states.
title When Do Riemann Solutions Consist of Rarefactions, Jumps, and Constants?
topic Analysis of PDEs
35L65, 35L67
url https://arxiv.org/abs/2605.21881