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SUMMARY:Active Taylor dispersion with Fourier methods: biased swimming cel
 ls with absorbing boundaries - Hakan Galdag
DTSTART:20240118T130000Z
DTEND:20240118T140000Z
UID:TALK210142@talks.cam.ac.uk
CONTACT:Lloyd Fung
DESCRIPTION:Shear induced dispersion of active matter is qualitatively dis
 tinct from the well-studied Taylor dispersion of passive particles. In app
 lications from bioreactors to biofilms\, active media involving biased swi
 mming particles is typically confined with complex boundary interactions. 
 Aris's method of moments has been hugely successful in predicting the effe
 ctive drift and diffusion along channels when no-flux conditions apply\, b
 ut struggles in cases with non-zero flux at boundaries for which active co
 mponents are not conserved\, requiring cumbersome calculations at higher o
 rders. Here\, we develop a Fourier approach that can side-step some of the
 se complexities to tackle a non-trivial class of active media problems wit
 h taxes and boundary interactions. The method is efficient and accessible.
  We challenge the predictions asymptotically with known results for leaky 
 pipes with cross-flows and numerically with Lagrangian simulations\, provi
 ding very good agreement for long-time and transient solutions. We find th
 at a strict ordering of eigenvalues is unnecessary to derive meaningful an
 alytical results. Interestingly\, for the case of two absorbing walls with
  biased motion towards one\, analysis reveals an optimal taxis strength fo
 r axial dispersion that desensitizes dependence on absorption rates. The F
 ourier approach opens a path for improved qualitative interpretation of re
 sults for this wide class of system.
LOCATION:MR15\,  Centre for Mathematical Sciences\, Wilberforce Road\, Cam
 bridge
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