Viscous Peeling Processes Under an Elastic Lid

Monday, May 11, 2015 - 2:00pm - 2:25pm
Keller 3-180
John Lister (University of Cambridge)
Consider an elastic sheet with a thin layer of viscous fluid between it and a rigid substrate. Peeling of the sheet away from the substrate, for example by injection of further fluid to form a blister, is an elastohydrodynamic problem with close links to the hydraulic-fracture problems such as laccolith formation by shallow intrusion of magma (e.g. Bunger & Cruden 2011). The rate of propagation, however, is controlled by the peeling process at the tip, rather than by fracture. Distinct propagation laws are found in the limits of peeling by bending stresses and peeling by pulling (tension), leading to radial growth as t^{7/22} and t^{3/8} respectively (Lister, Peng & Neufeld, 2013). In both regimes, detailed calculations give excellent agreement with experimental measurements of surface deflections. Interest in this system was prompted in part by the surprising observation (Pihler-Puzovic, Illien, Heil & Juel, 2012) that the Saffman-Taylor viscous-fingering instability resulting from injection of low-viscosity fluid can be suppressed by the elastic deformations. A detailed stability analysis identifies four physical mechanisms that contribute significantly to this suppression.