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Marseille, France

Morize C.,et Aix Marseille Universites | Morize C.,University Pierre and Marie Curie | Le Bars M.,et Aix Marseille Universites | Le Gal P.,et Aix Marseille Universites | And 2 more authors.
Physical Review Letters | Year: 2010

We describe a new phenomenon of zonal wind generation by tidal forcing. Following a recent theoretical and numerical analysis, we present the first experimental evidence that the nonlinear self-interaction of a tidally forced inertial mode can drive an intense axisymmetric flow in a rotating deformed sphere. Systematic measurements of zonal flows are carried out by an embarked system of particle image velocimetry, allowing the determination of general scaling laws. These results are fully relevant for zonal winds generation in planets and stars, and illustrate a generic mechanism of geostrophic flow generation by periodic forcing. © 2010 The American Physical Society. Source


Cebron D.,et Aix Marseille Universites | Le Bars M.,et Aix Marseille Universites | Leontini J.,Monash University | Maubert P.,et Aix Marseille Universites | Le Gal P.,et Aix Marseille Universites
Physics of the Earth and Planetary Interiors | Year: 2010

The full non-linear evolution of the tidal instability is studied numerically in an ellipsoidal fluid domain relevant for planetary cores applications. Our numerical model, based on a finite element method, is first validated by reproducing some known analytical results. This model is then used to address open questions that were up to now inaccessible using theoretical and experimental approaches. Growth rates and mode selection of the instability are systematically studied as a function of the aspect ratio of the ellipsoid and as a function of the inclination of the rotation axis compared to the deformation plane. We also quantify the saturation amplitude of the flow driven by the instability and calculate the viscous dissipation that it causes. This tidal dissipation can be of major importance for some geophysical situations and we thus derive general scaling laws which are applied to typical planetary cores. © 2010 Elsevier B.V. Source


Cebron D.,et Aix Marseille Universites | Le Bars M.,et Aix Marseille Universites | Meunier P.,et Aix Marseille Universites
Physics of Fluids | Year: 2010

The tilt-over mode in a precessing triaxial ellipsoid is studied theoretically and numerically. Inviscid and viscous analytical models previously developed for the spheroidal geometry by Poincaré [Bull. Astron.27, 321 (1910)] and Busse [J. Fluid Mech.33, 739 (1968)] are extended to this more complex geometry, which corresponds to a tidally deformed spinning astrophysical body. As confirmed by three-dimensional numerical simulations, the proposed analytical model provides an accurate description of the stationary flow in an arbitrary triaxial ellipsoid, until the appearance at more vigorous forcing of time dependent flows driven by tidal and/or precessional instabilities. © 2010 American Institute of Physics. Source

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