TY - JOUR

T1 - Imperfect Bifurcation for the Quasi-Geostrophic Shallow-Water Equations

AU - Dritschel, David Gerard

AU - Hmidi, Taoufik

AU - Renault, Coralie

N1 - Publisher Copyright:
© 2018, Springer-Verlag GmbH Germany, part of Springer Nature.

PY - 2019/3/7

Y1 - 2019/3/7

N2 - We study analytical and numerical aspects of the bifurcation diagram of simply connected rotating vortex patch equilibria for the quasi-geostrophic shallow-water (QGSW) equations. The QGSW equations are a generalisation of the Euler equations and contain an additional parameter, the Rossby deformation length ε- 1, which enters into the relation between the stream function and (potential) vorticity. The Euler equations are recovered in the limit ε→ 0. We prove, close to circular (Rankine) vortices, the persistence of the bifurcation diagram for arbitrary Rossby deformation length. However we show that the two-fold branch, corresponding to Kirchhoff ellipses for the Euler equations, is never connected even for small values ε, and indeed is split into a countable set of disjoint connected branches. Accurate numerical calculations of the global structure of the bifurcation diagram and of the limiting equilibrium states are also presented to complement the mathematical analysis.

AB - We study analytical and numerical aspects of the bifurcation diagram of simply connected rotating vortex patch equilibria for the quasi-geostrophic shallow-water (QGSW) equations. The QGSW equations are a generalisation of the Euler equations and contain an additional parameter, the Rossby deformation length ε- 1, which enters into the relation between the stream function and (potential) vorticity. The Euler equations are recovered in the limit ε→ 0. We prove, close to circular (Rankine) vortices, the persistence of the bifurcation diagram for arbitrary Rossby deformation length. However we show that the two-fold branch, corresponding to Kirchhoff ellipses for the Euler equations, is never connected even for small values ε, and indeed is split into a countable set of disjoint connected branches. Accurate numerical calculations of the global structure of the bifurcation diagram and of the limiting equilibrium states are also presented to complement the mathematical analysis.

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U2 - 10.1007/s00205-018-1312-7

DO - 10.1007/s00205-018-1312-7

M3 - Article

AN - SCOPUS:85055131213

SN - 0003-9527

VL - 231

SP - 1853

EP - 1915

JO - Archive for Rational Mechanics and Analysis

JF - Archive for Rational Mechanics and Analysis

IS - 3

ER -