Geometry-dependent viscosity reduction in sheared active fluids

Jonasz Słomka; Jörn Dunkel

doi:10.1103/physrevfluids.2.043102

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arXiv · 1608.01757

Geometry-dependent viscosity reduction in sheared active fluids

Jonasz Słomka·Jörn Dunkel

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Abstract

We investigate flow pattern formation and viscosity reduction mechanisms in active fluids by studying a generalized Navier-Stokes model that captures the experimentally observed bulk vortex dynamics in microbial suspensions. We present exact analytical solutions including stress-free vortex lattices and introduce a computational framework that allows the efficient treatment of previously intractable higher-order shear boundary conditions. Large-scale parameter scans identify the conditions for spontaneous flow symmetry breaking, geometry-dependent viscosity reduction and negative-viscosity states amenable to energy harvesting in confined suspensions. The theory uses only generic assumptions about the symmetries and long-wavelength structure of active stress tensors, suggesting that inviscid phases may be achievable in a broad class of non-equilibrium fluids by tuning confinement geometry and pattern scale selection.

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Jonasz Słomka, Jörn Dunkel. 2016-08-05. Geometry-dependent viscosity reduction in sheared active fluids. https://doi.org/10.1103/physrevfluids.2.043102

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