Walls inhibit chaotic mixing

Emmanuelle Gouillart (1) , N. Kuncio (1) , Olivier Dauchot (1) , Bérengère Dubrulle (1) , Stéphane Roux (2, 3) , Jean-Luc Thiffeault (4)

1 SPEC - UMR3680 - Service de physique de l'état condensé
2 SVI - Surface du Verre et Interfaces
3 LMT - Laboratoire de Mécanique et Technologie
4 Department of Mathematics [Imperial College London]

We report on experiments of chaotic mixing in a closed vessel, in which a highly viscous fluid is stirred by a moving rod. We analyze quantitatively how the concentration field of a low-diffusivity dye relaxes towards homogeneity, and observe a slow algebraic decay of the inhomogeneity, at odds with the exponential decay predicted by most previous studies. Visual observations reveal the dominant role of the vessel boundary, which strongly influences the concentration field in the entire domain and causes the anomalous scaling. A simplified 1-D model supports our experimental results. Quantitative analysis of the concentration pattern leads to scalings for the distributions and the variance of the concentration field consistent with experimental and numerical results.

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

Emmanuelle Gouillart, N. Kuncio, Olivier Dauchot, Bérengère Dubrulle, Stéphane Roux, et al.. Walls inhibit chaotic mixing. Physical Review Letters, 2007, 99 (11), pp.114501. ⟨10.1103/PhysRevLett.99.114501⟩. ⟨hal-00193177⟩