Experimental evidence of the anisotropy of tracer dispersion in rough fractures with sheared walls
Résumé
Dispersion experiments are compared for two transparent model fractures with identical complementary rough walls but with a relative shear displacement $\vec{\delta}$ parallel ($\vec{\delta}\parallel \vec{U}$) or perpendicular ($\vec{\delta} \perp \vec{U}$) to the flow velocity $\vec{U}$. The structure of the mixing front is characterized by mapping the local normalized local transit time $\bar t(x,y)$ and dispersivity $\alpha(x,y)$. For $\vec{\delta} \perp \vec{U}$, displacement fronts display large fingers: their geometry and the distribution of $\bar t(x,y)U/x$ are well reproduced by assuming parallel channels of hydraulic conductance deduced from the aperture field. For $\vec{\delta} \parallel \vec{U}$, the front is flatter and $\alpha(x,y)$ displays a narrow distribution and a Taylor-like variation with $Pe$.
Origine : Fichiers produits par l'(les) auteur(s)
Loading...