Experimental evidence for the boundary zonal flow in rotating Rayleigh-Bénard convection
Résumé
We report on the presence of the boundary zonal flow in rotating Rayleigh-Bénard convection evidenced by two-dimensional particle image velocimetry. Experiments were conducted in a cylindrical cell of aspect ratio between its diameter (D) and height (H) of Γ = D/H = 1. As the working fluid we used various mixtures of water and glycerol, leading to Prandtl numbers in the range 6.6 Pr 75. The horizontal velocity components were measured at a horizontal cross-section at half height. The Rayleigh numbers were in the range 10 8 Ra 3 × 10 9. The effect of rotation is quantified by the Ekman number which was between 1.5 × 10 −5 Ek 1.2 × 10 −3 in our experiment. With our results we show the first direct measurements of the boundary zonal flow-BZF that develops near the sidewall and was recently discovered in numerical simulations as well as in sparse and localized temperature measurements. We analyse the thickness δ 0 of the BZF as well as its maximal velocity as function of Pr , Ra, and Ek , and compare these results with previous DNS results.
Origine : Fichiers produits par l'(les) auteur(s)