Experimental and numerical study of mean zonal flows generated by librations of a rotating spherical cavity

Alban Sauret (1) , David Cébron (1) , Cyprien Morize (2) , Michael Le Bars (1)

1 IRPHE - Institut de Recherche sur les Phénomènes Hors Equilibre
2 FAST - Fluides, automatique, systèmes thermiques

We study both experimentally and numerically the steady zonal flow generated by longitudinal librations of a spherical rotating container. This study follows the recent weakly nonlinear analysis of Busse (2010), developed in the limit of small libration frequency - rotation rate ratio, and large libration frequency - spin-up time product. Using PIV measurements as well as results from axisymmetric numerical simulations, we confirm quantitatively the main features of Busse's analytical solution: the zonal flow takes the form of a retrograde solid body rotation in the fluid interior, which does not depend on the libration frequency nor on the Ekman number, and which varies as the square of the amplitude of excitation. We also report the presence of an unpredicted prograde flow at the equator near the outer wall.

Mots clés: Libration; Zonal flow

Domaines: Mécanique des fluides [physics.class-ph]; Mécanique des fluides [physics.class-ph]

Alban Sauret, David Cébron, Cyprien Morize, Michael Le Bars. Experimental and numerical study of mean zonal flows generated by librations of a rotating spherical cavity. Journal of Fluid Mechanics, 2010, 662, pp 260-268. ⟨10.1017/S0022112010004052⟩. ⟨hal-00603995⟩