Active Viscoelastic Matter: From Bacterial Drag Reduction to Turbulent Solids

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.

Publication
PHYSICAL REVIEW LETTERS 114, (2015).
Date
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