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Accueil > Équipes > Equipe MEIGE : Modélisation, Expériences et Instrumentation pour la Géophysique et l’Environnement > Diffusion scientifique > Séminaires internes

Spatially developing gravity currents onto concave slopes

Eletta Negretti, 04/12/14

Experimental results using a PIV measurement technique of gravity currents over concave slopes with different initial slope angles are presented. For large angles, the flow follows a periodic acceleration-deceleration cycle in which gravity and total friction (at the interface and at the bottom) interplay resulting in a strong spatial development of the gravity current. A theoretical model adapted for varying slope angles is presented and used for comparison with the experiments. Entrainment rates are twice larger as in previous similar studies and we estimate surprisingly large bottom friction coefficients. We explain these values with the observed large amplification rate of the Kelvin-Helmholtz instabilities at the interface, which grow until they completely dominate over the descending gravity flow. These results are compared to another set of experiments over a linear sloping bottom and we see that the observed spatial development is independent on the slope curvature.