Spontaneous mirror-symmetry breaking induces inverse energy cascade in 3D active fluids
Author(s)
Slomka, Jonasz Jozef; Dunkel, Joern
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Classical turbulence theory assumes that energy transport in a 3D turbulent flow proceeds through a Richardson cascade whereby larger vortices successively decay into smaller ones. By contrast, an additional inverse cascade characterized by vortex growth exists in 2D fluids and gases, with profound implications for meteorological flows and fluid mixing. The possibility of a helicitydriven inverse cascade in 3D fluids had been rejected in the 1970s based on equilibrium-thermodynamic arguments. Recently, however, it was proposed that certain symmetry-breaking processes could potentially trigger a 3D inverse cascade, but no physical system exhibiting this phenomenon has been identified to date. Here, we present analytical and numerical evidence for the existence of an inverse energy cascade in an experimentally validated 3D active fluid model, describing microbial suspension flows that spontaneously break mirror symmetry. We show analytically that self-organized scale selection, a generic feature of many biological and engineered nonequilibrium fluids, can generate parityviolating Beltrami flows. Our simulations further demonstrate how active scale selection controls mirror-symmetry breaking and the emergence of a 3D inverse cascade.
Date issued
2017-02Department
Massachusetts Institute of Technology. Department of MathematicsJournal
Proceedings of the National Academy of Sciences
Publisher
National Academy of Sciences (U.S.)
Citation
Słomka, Jonasz and Dunkel, Jörn. “Spontaneous Mirror-Symmetry Breaking Induces Inverse Energy Cascade in 3D Active Fluids.” Proceedings of the National Academy of Sciences 114, 9 (February 2017): 2119–2124 © 2017 National Academy of Sciences
Version: Final published version
ISSN
0027-8424
1091-6490