Self-similar concentration profiles in buoyant mixing of miscible fluids in a vertical tube

Marie Debacq (1) , Vincent Fanguet (1) , Jean-Pierre Hulin (1) , Dominique Salin (1) , Bernard Perrin (2)

1 FAST - Fluides, automatique, systèmes thermiques
2 LPA - Laboratoire Pierre Aigrain

The influence of the density contrast (characterized by the Atwood number At) on gravity-induced mixing between two miscible fluids in a long vertical tube has been studied experimentally. Cross-section averaged fluid concentration profiles along the tube are measured optically: for large enough At values, they display a self-similar dependence in a broad range of times and distances and verify a diffusion law with an effective diffusivity 105 times higher than for molecular diffusion. At lower At values, this diffusive domain is limited by a sharp front moving at a velocity increasing with At. Below a threshold At value the diffusive behavior disappears.

Domaines: Mécanique des fluides [physics.class-ph]; Génie des procédés

Marie Debacq, Vincent Fanguet, Jean-Pierre Hulin, Dominique Salin, Bernard Perrin. Self-similar concentration profiles in buoyant mixing of miscible fluids in a vertical tube. Physics of Fluids, 2001, 13 (11), pp.3097-3100. ⟨10.1063/1.1405442⟩. ⟨hal-00984190⟩