Abstract

This paper introduces the r-Camassa-Holm (r-CH) equation, which describes a geodesic flow on the manifold of diffeomorphisms acting on the real line induced by the W 1 , r metric. The conserved energy for the problem is given by the full W 1 , r norm. For r = 2, we recover the Camassa-Holm equation. We compute the Lie symmetries for r-CH and study various symmetry reductions. We introduce singular weak solutions of the r-CH equation for r ⩾ 2 and demonstrates their robustness in numerical simulations of their nonlinear interactions in both overtaking and head-on collisions. Several open questions are formulated about the unexplored properties of the r-CH weak singular solutions, including the question of whether they would emerge from smooth initial conditions.

Original languageEnglish
Pages (from-to)6199-6223
Number of pages25
JournalNonlinearity
Volume36
Issue number11
Early online date20 Oct 2023
DOIs
Publication statusPublished - 1 Nov 2023

Bibliographical note

Funding Information:
We would like to thank our friends and colleagues who have generously offered their attention, thoughts and encouragement in the course of this work during the time of COVID-19. We thank Jonathan Mestel for useful discussions about equation (), which kickstarted this work. C J C is grateful for partial support from EPSRC (EP/W015439/1, EP/W016125/1, EP/R029423/1, EP/R029628/1, EP/L016613/1) and NERC (NE/R008795/1). D H is grateful for partial support from ERC Synergy Grant 856408—STUOD (Stochastic Transport in Upper Ocean Dynamics). T P is grateful for partial support from EPSRC (EP/X017206/1, EP/X030067/1 and EP/W026899/1) and the Leverhulme Trust (RPG-2021-238).

Data availability statement: No new data were created or analysed in this study.

Keywords

  • 35Q53
  • 37K05
  • 37K06
  • 37K58
  • Camassa-Holm equation
  • peakons
  • singular solutions

ASJC Scopus subject areas

  • Statistical and Nonlinear Physics
  • Mathematical Physics
  • General Physics and Astronomy
  • Applied Mathematics

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