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American Geophysical Union, Geophysical Research Letters, 17(41), p. 6078-6083

DOI: 10.1002/2014gl061434

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Tide driven shear instability in planetary liquid cores

Journal article published in 2014 by Alban Sauret, Michael Le Bars, Patrice Le Gal ORCID
This paper is made freely available by the publisher.
This paper is made freely available by the publisher.

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Abstract

We present an experimental study on the shear instability driven by tidal forcing in a model planetary liquid core. The experimental set-up consists of a water-filled deformable sphere rotating around its axis and subjected to an elliptical forcing. At resonant forcing frequencies, the nonlinear self-interaction of the excited inertial mode drives an intense and localized axisymmetric jet. The jet becomes unstable at low Ekman number because of a shear instability. Using particle image velocimetry measurements, we derive a semi-empirical scaling law that captures the instability threshold of the shear instability. This mechanism is fully relevant to planetary systems, where it constitutes a new route to generate turbulence in their liquid cores.