Stick-slip instability for viscous fingering in a gel

N. Puff (1) , G. Debregeas (1) , J. -M. Di Meglio (1) , D. Higgins (1) , C. Wagner (2) , D. Bonn (2)

1 ICS - Institut Charles Sadron
2 LPS - Laboratoire de Physique Statistique de l'ENS

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: Matière Molle [cond-mat.soft]

N. Puff, G. Debregeas, J. -M. Di Meglio, D. Higgins, C. Wagner, et al.. Stick-slip instability for viscous fingering in a gel. EPL - Europhysics Letters, 2002, 58, pp.524-529. ⟨hal-00136001⟩