Active Viscoelastic Matter: From Bacterial Drag Reduction to Turbulent Solids

E. J. Hemingway, A. Maitra, S. Banerjee, M. C. Marchetti, S. Ramaswamy, S. M. Fielding, and M. E. Cates

Phys. Rev. Lett. 114, 098302 – Published 5 March 2015

Abstract

A paradigm for internally driven matter is the active nematic liquid crystal, whereby the equations of a conventional nematic are supplemented by a minimal active stress that violates time-reversal symmetry. In practice, active fluids may have not only liquid-crystalline but also viscoelastic polymer degrees of freedom. Here we explore the resulting interplay by coupling an active nematic to a minimal model of polymer rheology. We find that adding a polymer can greatly increase the complexity of spontaneous flow, but can also have calming effects, thereby increasing the net throughput of spontaneous flow along a pipe (a “drag-reduction” effect). Remarkably, active turbulence can also arise after switching on activity in a sufficiently soft elastomeric solid.

Received 22 October 2014

DOI:https://doi.org/10.1103/PhysRevLett.114.098302

Authors & Affiliations

E. J. Hemingway¹, A. Maitra², S. Banerjee^3,4, M. C. Marchetti³, S. Ramaswamy^5,2, S. M. Fielding¹, and M. E. Cates⁶

¹Department of Physics, Durham University, Science Laboratories, South Road, Durham DH1 3LE, United Kingdom
²CCMT, Department of Physics, Indian Institute of Science, Bangalore 560 012, India
³Physics Department and Syracuse Biomaterials Institute, Syracuse University, Syracuse, New York 13244, USA
⁴James Franck Institute, University of Chicago, Chicago, Illinois 60637, USA
⁵TIFR Centre for Interdisciplinary Sciences, 21 Brundavan Colony, Osman Sagar Road, Narsingi, Hyderabad 500 075, India
⁶SUPA, School of Physics and Astronomy, University of Edinburgh, James Clerk Maxwell Building, Peter Guthrie Tait Road, Edinburgh EH9 3FD, United Kingdom