Stick-slip instability for viscous fingering in a gel
Résumé
Non-Newtonian fluid flows. PACS. 82.70.Gg-Gels and sols. PACS. 83.60.Wc-Flow instabilities. Abstract.-The growth dynamics of an air finger injected in a visco-elastic gel (a PVA/borax aqueous solution) is studied in a linear Hele-Shaw cell. Besides the standard Saffmann-Taylor instability, we observe-with increasing finger velocities-the existence of two new regimes: (a) a stick-slip regime for which the finger tip velocity oscillates between 2 different values, producing local pinching of the finger at regular intervals, (b) a "tadpole" regime where a fracture-type propagation is observed. A scaling argument is proposed to interpret the dependence of the stick-slip frequency with the measured rheological properties of the gel.
Domaines
Biophysique [physics.bio-ph]
Origine : Fichiers produits par l'(les) auteur(s)
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