Shearing Active Gels Close to the Isotropic-Nematic Transition

• DOI: 10.1103/physrevlett.101.068102
• Publication Date: 2008-08-08T19:57:03Z
• Authors: M. E. Cates; S. M. Fielding; D. Marenduzzo; E. Orlandini; J. M. Yeomans
• Keywords: Viscosity; FOS: Physical sciences; Condensed Matter - Soft Condensed Matter; 01 natural sciences; Models, Chemical; Nonlinear Dynamics; 0103 physical sciences; Soft Condensed Matter (cond-mat.soft); Rheology; Gels; Algorithms

We study numerically the rheological properties of a slab of active gel close o the isotropic-nematic transition. The flow behavior shows strong dependence on sample size, boundary conditions, and on the bulk constitutive curve, which, on entering the nematic phase, acquires an activity-induced discontinuity at the origin. The precursor of this within the metastable isotropic phase for contractile systems ({\em e.g.,} actomyosin gels) gives a viscosity divergence; its counterpart for extensile ({\em e.g.,} {\em B. subtilis}) suspensions admits instead a shear-banded flow with zero apparent viscosity.<br/>4 pages, 5 figures<br/>