Dispersion enhancement and damping by buoyancy driven flows in 2D networks of capillaries

Maria Veronica d'Angelo (1, 2) , Harold Auradou (1) , Catherine Allain (1) , Marta Rosen (2) , Jean-Pierre Hulin (1)

1 FAST - Fluides, automatique, systèmes thermiques
2 GMP - Grupo de Medios Porosos [Buenos Aires]

The influence of a small relative density difference on the displacement of two miscible liquids is studied experimentally in transparent 2D networks of micro channels. Both stable displacements in which the denser fluid enters at the bottom of the cell and displaces the lighter one and unstable displacements in which the lighter fluid is injected at the bottom and displaces the denser one are realized. Except at the lowest mean flow velocity U, the average $C(x,t)$ of the relative concentration satisfies a convection-dispersion equation. The dispersion coefficient is studied as function of the relative magnitude of fluid velocity and of the velocity of buoyancy driven fluid motion. A model is suggested and its applicability to previous results obtained in $3D$ media is discussed.

Mots clés: buoyancy; flow instability; porous media; hydrodynamic dispersion

Domaines: Dynamique des Fluides [physics.flu-dyn]

Maria Veronica d'Angelo, Harold Auradou, Catherine Allain, Marta Rosen, Jean-Pierre Hulin. Dispersion enhancement and damping by buoyancy driven flows in 2D networks of capillaries. Physics of Fluids, 2008, 20, pp.034107. ⟨10.10631/1.2899635⟩. ⟨hal-00282967⟩