Evolution of a barotropic shear layer into elliptical vortices

Anirban Guha (Lead / Corresponding author), Mona Rahmani, Gregory A. Lawrence

Research output: Contribution to journalArticle

10 Citations (Scopus)

Abstract

When a barotropic shear layer becomes unstable, it produces the well-known Kelvin-Helmholtz instability (KHI). The nonlinear manifestation of the KHI is usually in the form of spiral billows. However, a piecewise linear shear layer produces a different type of KHI characterized by elliptical vortices of constant vorticity connected via thin braids. Using direct numerical simulation and contour dynamics, we show that the interaction between two counterpropagating vorticity waves is solely responsible for this KHI formation. We investigate the oscillation of the vorticity wave amplitude, the rotation and nutation of the elliptical vortex, and straining of the braids. Our analysis also provides a possible explanation for the formation and evolution of elliptical vortices appearing in geophysical and astrophysical flows, e.g., meddies, stratospheric polar vortices, Jovian vortices, Neptune's Great Dark Spot, and coherent vortices in the wind belts of Uranus.

Original languageEnglish
Article number013020
JournalPhysical Review E - Statistical, Nonlinear, and Soft Matter Physics
Volume87
Issue number1
Early online date29 Jan 2013
DOIs
Publication statusPublished - Jan 2013

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