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SUMMARY:Hydrodynamics of active defects - Cristina Marchetti\, UCSB
DTSTART:20190507T120000Z
DTEND:20190507T130000Z
UID:TALK122170@talks.cam.ac.uk
CONTACT:Professor Mike Cates
DESCRIPTION: Topological defects play a prominent role in the physics of t
 wo-dimensional materials.  When driven out of equilibrium in active nemati
 cs\, disclinations can acquire spontaneous self-propulsion and proliferate
  to drive self-sustained flows.  In this talk I will describe the derivati
 on of an interacting particle description of defects that includes active 
 torques and show that activity drives a non-equilibrium variant of the Ber
 ezinskii Kosterlitz-Thouless defect-unbinding transition.  On scales large
 r than the defect separation\, the dynamics of the gas of unbound defects 
 can be described by hydrodynamic equations derived by coarse-graining the 
 defects microdynamics.  At high activity\, nonequilibrium torques combined
  with many-body screening cause the active disclinations to spontaneously 
 break rotational symmetry\, forming a collectively moving defect ordered p
 olar liquid.  Finally\, I will show that the hydrodynamic theory provides 
 an excellent framework for treating inhomogeneous activity that can be use
 d to pattern and control the dynamics of defects in active fluids.
LOCATION:MR11\, CMS
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