Bioconvection Patterns
Jeudi 12 février 2015 14:00
- Duree : 1 heure
Lieu : Conference room - LIPhy - Bât E - 140 Avenue de la Physique - St Martin d’Hères. Accès par interphone, appeler le secrétariat
Orateur : Nick HILL (School of Mathematics & Statistics, University of Glasgow, U.K.)
Fourier analysis [1] has been used successfully to measure pattern wavelengths generated by suspensions of swimming micro‐organisms (bioconvection) and thus to quantify the changes that are seen as the patterns evolve in time. To identify and analyse such local variation, we have developed techniques from wavelet theory that give measures of the local pattern wavelengths and the principal directions of the lines of symmetry.
Secondly, computational fluid dynamics is used to investigate pattern formation by swimming microorganisms, when their orientation is determined by balance between gravitational and viscous torques (gyrotaxis), due to being bottom-heavy. The governing equations, which consist of the Navier–Stokes equations for an incompressible fluid coupled with a micro-organism conservation equation, are solved numerically in a large cross-section chamber with periodic boundary conditions in the horizontal directions.
[1] Bees, M.A. & Hill, N.A. Wavelengths of Bioconvection Patterns. Journal of Experimental Biology, 200, 1515-‐1526, (1997).
Contact : philippe.peyla@ujf-grenoble.fr
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