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SUMMARY:Self-organized patterns in active turbulence and ensembles of acti
 ve particles - Michael Wilczek (Universität Bayreuth)
DTSTART:20240614T130000Z
DTEND:20240614T135000Z
UID:TALK214795@talks.cam.ac.uk
DESCRIPTION:In this talk\, I am going to review some of our recent works o
 n large-scale patterns in active fluids. In the first part\, we will consi
 der a simple model for polar active fluids which is well-known for exhibit
 ing active turbulence [1]. Using large-scale computations we show that als
 o self-organized vortex crystals can emerge after a turbulent transient [2
 \,3]\, similar to recent observations in two-dimensional forced Navier-Sto
 kes turbulence [4].The second part of the talk focuses on active nematic t
 urbulence [5]. We show that in certain parameter ranges for the active and
  elastic properties of the fluid the usual Stokes approximation breaks dow
 n and large-scale flow patterns can emerge due to an inverse transport of 
 energy to large scales [6].In the final part of the presentation\, I will 
 take a more microscopic perspective and present ongoing work on disk-like 
 active Brownian particles in which the geometric centers do not coincide w
 ith the centers of mass. This property leads to torques even for simple st
 eric interaction\, which can significantly affect large-scale aggregation 
 phenomena in this model.\n[1] Wensink\, Dunkel\, Heidenreich\, Drescher\, 
 Goldstein\, L&ouml\;wen\, Yeomans. Meso-scale turbulence in living fluids\
 , PNAS 109\, 14308 (2012)[2] James\, Bos\, Wilczek\, Turbulence and turbul
 ent pattern formation in a minimal model for active fluids\, Phys. Rev. Fl
 uids 3\, 061101(R) (2018)[3] James\, Suchla\, Dunkel\, Wilczek\, Emergence
  and melting of active vortex crystals\, Nat. Commun. 12\, 5630 (2021)[4] 
 van Kan\, Favier\, Julien\, Knobloch\, From a vortex gas to a vortex cryst
 al in instability-driven two-dimensional turbulence\,&nbsp\;J. Fluid Mech.
  984\, A41 (2024)[5] Giomi\, Geometry and topology of turbulence in active
  nematics Physical Review X 5\, 031003 (2015)[6] Koch & Wilczek\, Role of 
 Advective Inertia in Active Nematic Turbulence\, PRL 127\, 268005 (2021)
LOCATION:Seminar Room 1\, Newton Institute
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