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ReinaudDritschel2003-JFluidMech474-Shape.pdf1.03 MBAdobe PDFView/Open
Title: The shape of vortices in quasi-geostrophic turbulence
Authors: Reinaud, Jean Noel
Dritschel, David Gerard
Koudella, CR
Keywords: Ellipsoidal vortices
Stratified fluid
QA Mathematics
Issue Date: 10-Jan-2003
Citation: Reinaud , J N , Dritschel , D G & Koudella , C R 2003 , ' The shape of vortices in quasi-geostrophic turbulence ' Journal of Fluid Mechanics , vol 474 , pp. 175-192 . , 10.1017/S0022112002002719
Abstract: The present work discusses the most commonly occurring shape of the coherent vortical structures in rapidly rotating stably stratified turbulence, under the quasi-geostrophic approximation. In decaying turbulence, these vortices-coherent regions of the materially-invariant potential vorticity-dominate the flow evolution, and indeed the flow evolution is governed by their interactions. An analysis of several exceptionally high-resolution simulations of quasi-geostrophic turbulence is performed. The results indicate that the population of vortices exhibits a mean height-to-width aspect ratio less than unity, in fact close to 0.8. This finding is justified here by a simple model, in which vortices are taken to be ellipsoids of uniform potential vorticity. The model focuses on steady ellipsoids within a uniform background strain flow. This background flow approximates the effects of surrounding vortices in a turbulent flow on a given vortex. It is argued that the vortices which are able to withstand the highest levels of strain are those most likely to be found in the actual turbulent flow. Our calculations confirm that the optimal height-to-width aspect ratio is close to 0.8 for a wide range of background straining flows.
Version: Publisher PDF
Description: Partially supported by the UK EPSRC (Grant GR/N11711)
Status: Peer reviewed
ISSN: 0022-1120
Type: Journal article
Rights: (c)2003 Cambridge University Press
Appears in Collections:University of St Andrews Research
Applied Mathematics Research

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