Expansion shock waves in regularized shallow water theory

Gennady El, Mark Hoefer, Michael Shearer

Research output: Contribution to journalArticlepeer-review

12 Citations (Scopus)


We identify a new type of shock wave by constructing a stationary expansion shock solution of a class of regularized shallow-water equations that include the Benjamin–Bona–Mahony and Boussinesq equations. An expansion shock exhibits divergent characteristics, thereby contravening the classical Lax entropy condition. The persistence of the expansion shock in initial value problems is analysed and justified using matched asymptotic expansions and numerical simulations. The expansion shock's existence is traced to the presence of a non-local dispersive term in the governing equation. We establish the algebraic decay of the shock as it is gradually eroded by a simple wave on either side. More generally, we observe a robustness of the expansion shock in the presence of weak dissipation and in simulations of asymmetric initial conditions where a train of solitary waves is shed from one side of the shock.
Original languageEnglish
Article number20160141
JournalProceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences
Issue number2189
Early online date1 May 2016
Publication statusPublished - 31 May 2016


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