Elliptic instability in the Lagrangian-averaged Euler-Boussinesq-alpha equations
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Published version
Author(s)
Fabijonas, BR
Holm, DD
Type
Journal Article
Abstract
We examine the effects of turbulence on elliptic instability of rotating stratified incompressible flows, in the context of the Lagrangian-averaged Euler–Boussinesq-α (LAEB-α) model of turbulence. We find that the LAEB-α model alters the instability in a variety of ways for fixed Rossby number and Brunt–Väisälä frequency. First, it alters the location of the instability domains in the (γ,cosθ)-parameter plane, where θ is the angle of incidence the Kelvin wave makes with the axis of rotation and γ is the eccentricity of the elliptic flow, as well as the size of the associated Lyapunov exponent. Second, the model shrinks the width of one instability band while simultaneously increasing another. Third, the model introduces bands of unstable eccentric flows when the Kelvin wave is two dimensional. We introduce two similarity variables—one is a ratio of the Brunt–Väisälä frequency to the model parameter Υ0=1+α2β2 and the other is the ratio of the adjusted inverse Rossby number to the same model parameter. Here, α is the turbulence correlation length and β is the Kelvin wave number. We show that by adjusting the Rossby number and Brunt–Väisälä frequency so that the similarity variables remain constant for a given value of Υ0, turbulence has little effect on elliptic instability for small eccentricities (∣γ∣⪡1). For moderate and large eccentricities, however, we see drastic changes of the unstable Arnold tongues due to the LAEB-α model. Additionally, we find that introducing anisotropy in the vertical component of the transported velocity field merely alters the definition of the model parameter Υ0, which effectively reduces the original parameter value. When the similarity variables are viewed with the new definition, the results are similar to those for the isotropic case.
Date Issued
2005-05-01
Date Acceptance
2005-02-15
Citation
Physics of Fluids, 2005, 17 (5)
ISSN
1070-6631
Publisher
AIP Publishing
Journal / Book Title
Physics of Fluids
Volume
17
Issue
5
Copyright Statement
© 2005 American Institute of Physics.
Identifier
http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcApp=PARTNER_APP&SrcAuth=LinksAMR&KeyUT=WOS:000229073700029&DestLinkType=FullRecord&DestApp=ALL_WOS&UsrCustomerID=1ba7043ffcc86c417c072aa74d649202
Subjects
Science & Technology
Technology
Physical Sciences
Mechanics
Physics, Fluids & Plasmas
Physics
3-DIMENSIONAL INSTABILITY
STRAINED VORTICES
FLUID
TURBULENCE
FLOWS
STABILITY
MODELS
WAVES
Publication Status
Published
Article Number
054113
Date Publish Online
2005-05-05