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SUMMARY:Orientation mixing in active suspensions - Helge Dietert (Paris Di
 derot)
DTSTART:20220613T130000Z
DTEND:20220613T140000Z
UID:TALK175337@talks.cam.ac.uk
CONTACT:Daniel Boutros
DESCRIPTION:I will present a popular kinetic model introduced by Saintilla
 n and Shelley for the dynamics of suspensions of active elongated particle
 s. This model\, involving the distribution in space and orientation of the
  particles\, is known to exhibit phase transitions. We focus on the linear
  analysis of incoherence\, that is on the linearized equation around the u
 niform distribution\, in the regime of parameters corresponding to spectra
 l (neutral) stability. I will show that in the absence of rotational diffu
 sion\, the supension experiences a mixing phenomenon similar to Landau dam
 ping\, and we provide optimal pointwise in time decay rates in weak topolo
 gy. We show that this phenomenon persists for small rotational diffusion\,
  and is combined with an enhanced dissipation at time scale $\\nu^{-1/2}$.
  The mathematical interest of the model is that the usual velocity variabl
 e of kinetic models is replaced by an orientation variable on the sphere. 
 The associated orientation mixing leads to limited algebraic decay for mac
 roscopic quantities.\n\nJoint work with Michele Coti Zelati and David Gér
 ard-Varet
LOCATION:CMS\, MR13
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