Precession-driven flows in non-axisymmetric ellipsoids

Jerome Noir (1) , David Cébron (2)

1 Institut für Geophysik [Zürich]
2 ISTerre - Institut des Sciences de la Terre

We study the flow forced by precession in rigid non-axisymmetric ellipsoidal containers. To do so, we revisit the inviscid and viscous analytical models that have been previously developed for the spheroidal geometry by, respectively, Poincaré (Bull. Astronomique, vol. XXVIII, 1910, pp. 1-36) and Busse (J. Fluid Mech., vol. 33, 1968, pp. 739-751), and we report the first numerical simulations of flows in such a geometry. In strong contrast with axisymmetric spheroids, where the forced flow is systematically stationary in the precessing frame, we show that the forced flow is unsteady and periodic. Comparisons of the numerical simulations with the proposed theoretical model show excellent agreement for both axisymmetric and non-axisymmetric containers. Finally, since the studied configuration corresponds to a tidally locked celestial body such as the Earth's Moon, we use our model to investigate the challenging but planetary-relevant limit of very small Ekman numbers and the particular case of our Moon.

Mots clés: geophysical and geological flows; topographic effects; wave in rotating fluids

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

Jerome Noir, David Cébron. Precession-driven flows in non-axisymmetric ellipsoids. Journal of Fluid Mechanics, 2013, 737, pp.412-439. ⟨hal-00926731⟩