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Colloquium: Dr. Jorn Dunkel , Massachusetts Inst. of Tech

Wednesday, November 20, 2019
3:30 PM - 4:30 PM
Physics : 401
TITLE:  Symmetry breaking in active and quantum fluids


Active biological fluids, such as bacterial and other microbial suspensions, can exhibit striking symmetry breaking phenomena, from the spontaneous formation of vortex lattices to the emergence of large-scale unidirectional flows. Borrowing ideas from classical pattern formation theory [1], I will discuss  generalized Navier-Stokes (GNS) equations [2-5] for active fluids that capture many of the experimentally observed phenomena. The GNS model permits exact stress-free bulk solutions, which include Abrikosov-type lattices in 2D [2,3] and Beltrami flows in 3D [4]. A triad analysis shows that the combination of a generic linear instability and a standard advective nonlinearity can give rise to spontaneous chiral symmetry breaking that supports inverse energy transport in 3D [4,5]. In the second part, we extend the underlying concepts to quantum fluids by deriving a higher-order generalization of the Gross-Pitaevskii model to study supersolid crystals and quasi-crystals [6].

[1] Stoop, et al. Nature Materials 14, 337 (2015)
[2] Slomka and Dunkel. Phys Rev Fluids 2, 043102 (2017)
[3] Mickelin, Slomka, et al. Phys Rev Lett 120, 164503 (2018) 
[4] Slomka and Dunkel. PNAS 114, 2119 (2017) 
[5] Slomka, Suwara and Dunkel. J Fluid Mech 841, 701 (2018)
[6] Heinonen, Burns and Dunkel. Phys Rev A 99, 063621 (2019)