Laboratoire de Mécanique des Fluides et d'Acoustique - UMR 5509

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Accueil > Actualités > Séminaires > Archives 2019

Benjamin MIQUEL, CEA Saclay

Variations on convective flows : from rotationally constrained flows in spheres to internal heat sources

Vendredi 15 Novembre 2019, 11h, salle 14, Bat W1bis ECL

Variations on convective flows : from rotationally constrained flows in spheres to internal heat sources

Buoyancy resulting from thermal or compositional inhomogeneities is a most important source of energy for natural turbulent flows. In this talk, I will present results on two paradigms that are of interest for geo- and astrophysical situations.
In differentially-heated rapidly rotating spherical shells, such as the global ocean of the icy moons Enceladus and Europa, the rotation-induced anisotropy of the flow (the Proudman-Taylor theorem) has the potential to suppress the convective instability at the pole, where global rotation is normal to the layer of fluid. Thus, convective flows are localized at the equator where the Proudman-Taylor constraint leads to the formation of latitudinally trapped convective cells. I will discuss a fully non linear, asymptotically reduced model that leverages rapid rotation and is amenable to a numerical resolution.
Time permits, I will discuss recent results on convection in presence of volumic sources in the plane layer geometry. In particular, the heat flux as measured by the Nusselt number is shown to vary as a power law with both the temperature difference (i.e. Rayleigh number) and the diffusivity ratio (Prandtl number). In presence of volumic sources, the exponents observed in both experiments and numerical simulations differ significantly from Rayleigh-Benard (wall-heated) convection, and different regimes are observed.


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