Bulk Elastic Fingering in Soft Materials

ORAL

Abstract

Systematic experiments have been performed in purely elastic polyacrylamide gels in Hele-Shaw cells. We have shown that a bulk fingering instability arises in the highly deformable confined elastomers. A systematic study shows that surface tension is not relevant. This instability is sub-critical, with a clear hysteretic behavior. Our experimental observations have been compared very favorably to theoretical and finite element simulations results. In particular, the instability wavelength and the critical front advance have been shown to be proportional to the distance between the two glass plates constituting the cell. A very important feature is that elasticity doesn't influence this lengthscale, making this instability very generic. We will also show some new results about an elastic counterpart experiment of the famous Saffman-Taylor experiment, where we push a soft gel in a stiff one.

–

Authors

  • Baudouin Saintyves

    • SEAS, Harvard University, Cambridge, MA, USA
    • Harvard
    • Harvard University

  • John Biggins

    • University of Cambridge
    • Cambridge University

  • Zhiyan Wei

    • Stanford
    • Stanford University

  • Serge Mora

    • Montpellier 2 University

  • L. Mahadevan

    • Harvard School of Engineering and Applied Science
    • Harvard University
    • SEAS, Harvard University, Cambridge, MA, USA
    • Harvard
    • School of Engineering and Applied Sciences, Harvard University, Cambridge, MA 02138,USA.
    • SEAS, Department of organismic and evolutionary biology, Harvard university
    • SEAS, Harvard University
    • Harvard Univ
    • School of Engineering and Applied Sciences, Wyss Institute, Harvard University

  • Elisabeth Bouchaud

    • ESPCI-PARISTECH