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SUMMARY:Continuum Model for Collective Behaviour of Micro-Swimmers - Lloyd
  Fung (Imperial College London)
DTSTART:20190131T130000Z
DTEND:20190131T140000Z
UID:TALK116902@talks.cam.ac.uk
CONTACT:Anne Herrmann
DESCRIPTION:The key to quantify phenomena such as gyrotactic plume formati
 on and bioconvection requires a macroscopic view of their collective behav
 iour. Instead of modelling micro-swimmers individually\, one can model the
  collective as a continuum using an advection-diffusion-typed equation. Us
 ing the gyrotactic swimmer\, Dunaliella salina\, in a downflowing pipe (Ke
 ssler\, 1986 JFM) as an example setup\, I am going to discuss the success 
 and challenges in developing the continuum model. The advantage of the con
 tinuum equation is that one can couple swimmers with non-linear flow patte
 rn like bioconvection with the full Navier-Stokes equation for the flow. H
 owever\, the challenge lies in the lack of an accurate model for the effec
 tive diffusivity of these swimmers. The earlier model by Prof. Pedley (Ped
 ley & Kessler\, 1990 JFM) is not as accurate at high shear\, while the rec
 ent model using Generalised Taylor Dispersion (GTD)\, although accurate in
  some cases (Croze et al.\, 2017 JFM)\, fails at strain-dominant region (B
 earon et al.\, 2011 JFM). Lastly\, I am going to present a roadmap towards
  a Direct Numerical Simulation of the suspension of swimmers. 
LOCATION:MR11\, Centre for Mathematical Sciences\, Wilberforce Road\, Camb
 ridge
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