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Spontaneous generation of inertial waves from boundary turbulence in a librating sphere

Published online by Cambridge University Press:  11 July 2013

Alban Sauret ,
David Cébron  and
Michael Le Bars
Alban Sauret*
Affiliation:
Institut de Recherche sur les Phénomènes Hors Équilibre, CNRS and Aix-Marseille University, 49 rue F. Joliot-Curie, F-13013 Marseille, France
David Cébron
Affiliation:
Institut de Recherche sur les Phénomènes Hors Équilibre, CNRS and Aix-Marseille University, 49 rue F. Joliot-Curie, F-13013 Marseille, France Institut fur Geophysik, ETH Zürich, Sonneggstrasse 5, CH-8092 Zürich, Switzerland
Michael Le Bars
Affiliation:
Institut de Recherche sur les Phénomènes Hors Équilibre, CNRS and Aix-Marseille University, 49 rue F. Joliot-Curie, F-13013 Marseille, France Department of Earth and Space Sciences, University of California, Los Angeles, CA 90095-1567, USA
*
†Email address for correspondence: asauret@princeton.edu
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Abstract

In this work, we report the excitation of inertial waves in a librating sphere even for libration frequencies where these waves are not directly forced. This spontaneous generation comes from the localized turbulence induced by the centrifugal instabilities in the Ekman boundary layer near the equator and does not depend on the libration frequency. We characterize the key features of these inertial waves in analogy with previous studies of the generation of internal waves in stratified flows from localized turbulent patterns. In particular, the temporal spectrum exhibits preferred values of excited frequency. This first-order phenomenon is generic to any rotating flow in the presence of localized turbulence and is fully relevant for planetary applications.

JFM classification

Geophysical and Geological Flows: Geophysical and Geological Flows Geophysical and Geological Flows: Rotating flows

Information

Type
Rapids
Information
Journal of Fluid Mechanics , Volume 728 , 10 August 2013 , R5
Copyright
©2013 Cambridge University Press 

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