Elliptical instability in a rotating spheroid

LB Lacaze, P Le Gal, S Le Dizes

Research output: Contribution to journalArticle (Academic Journal)peer-review

55 Citations (Scopus)

Abstract

This paper concerns the elliptical instability of a flow in a rotating deformed sphere. The aim of our work is to analyse the characteristics of this instability experimentally and to provide a theoretical model which accounts for the observations. For this purpose, an elastic and transparent hollow sphere has been moulded in a silicone gel block. The flow is visualized using Kalliroscope flakes illuminated with a laser sheet as the sphere is set into rotation and compressed by two rollers. The elliptical instability occurs by the appearance of the so-called 'spin-over' mode whose growth rate and saturation amplitude are measured by video image analysis at different Ekman numbers. Growth rates are predicted well by the linear stability analysis. A nonlinear model is developed and is shown to describe correctly the saturated regimes observed in the experiments. At low Ekman numbers, a secondary instability leading to an intermittent regime is also discovered.
Translated title of the contributionElliptical instability in a rotating spheroid
Original languageEnglish
Pages (from-to)1 - 22
Number of pages22
JournalJournal of Fluid Mechanics
Volume505
DOIs
Publication statusPublished - Apr 2004

Bibliographical note

Publisher: Cambridge Univ Press

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