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SUMMARY:Particle displacements by swimming organisms - Jean-Luc Thiffeault
 \, University of Wisconsin
DTSTART:20150219T130000Z
DTEND:20150219T140000Z
UID:TALK57828@talks.cam.ac.uk
CONTACT:Julius Bier Kirkegaard
DESCRIPTION:The experiments of Leptos et al. [Phys. Rev. Lett. 103\, 19810
 3 (2009)] show that the displacements of small particles affected by swimm
 ing microorganisms achieve a non-Gaussian distribution\, which nevertheles
 s scales diffusively.  We use a simple model where the particles undergo r
 epeated `kicks' due to the swimmers to explain the shape of the distributi
 on as a function of the volume fraction of swimmers.  The net displacement
  is determined by the self-convolution of the drift function caused by one
  swimmer\, and a Poisson distribution for the frequency of interactions.  
 The only adjustable parameter is the strength of the stresslet term in our
  spherical squirmer model.  The effective diffusivity measured in the expe
 riments is consistent with the model\, with no further parameter adjustmen
 ts. 
LOCATION:MR14\,  Centre for Mathematical Sciences\, Wilberforce Road\, Cam
 bridge
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