2001/03/21 by Georges Debregeas, Herve Tabuteau, Jean-Marc di Meglio · 1 citation
Physics and Astronomy · #cond-mat.mtrl-sci #cond-mat.soft #cond-mat.stat-mech
paper · pdf · doi:10.1103/physrevlett.87.178305
published as Phys. Rev. Lett. 87, 178305 (2001) · 5 pages, 2 figures
arxiv created 2001/03/21 · arxiv updated 2009/11/30
We investigate the flow properties of a two-dimensional aqueous foam submitted to a quasistatic shear in a Couette geometry. A strong localization of the flow (shear banding) at the edge of the moving wall is evidenced, characterized by an exponential decay of the average tangential velocity. Moreover, the analysis of the rapid velocity fluctuations reveals self-similar dynamical structures consisting of clusters of bubbles rolling as rigid bodies. To relate the instantaneous (elastic) and time-averaged (plastic) components of the strain, we develop a stochastic model where irreversible rearrangements are activated by local stress fluctuations originating from the rubbing of the wall. This model gives a complete description of our observations and is also consistent with data obtained on granular shear bands by other groups.