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BP: Fachverband Biologische Physik

BP 32: Posters: Other Topics in Biological Physics

BP 32.5: Poster

Donnerstag, 17. März 2011, 17:15–20:00, P3

A simple three-point-force model for Chlamydomonas Reinhardti — •Ruud Boesten^1,2, Holger Stark¹, and Ignacio Pagonabarraga³ — ¹TU Berlin, Germany — ²TU Eindhoven, Netherlands — ³University of Barcelona, Spain

There is an abundance of swimming organisms on the micrometer scale. From unicellar algae in the oceans, to pathogenic bacteria in human blood vessels. The motility of these microorganisms affects macroscopic properties. For suspensions of Bactilus Subtili a decrease of the viscosity has been measured with respect to the viscosity of the suspending medium [1]. In contrast, for suspensions of Chlamydomonas Reinhardti (CR) an increase was measured [2]. Very recently, on the millisecond time and micrometer length scale the flow field of several micro-swimmers has been measured [3]. The understanding of these phenomena on all length and time scales could give us information about the behaviour and role of micro swimming in a broad range of environments.

Inertial forces are small compared to viscous forces on the size of a microorganism. We investigated a simple 3-point-force model for CR. The resulting flow field is the superposition of the 3 induced stokeslets. This model can explain both the flow field within a beat cycle on the length scale of several body lengths, as well as the effective viscosity of a suspension of CRs on large time scales.

[1] Sokolov et al., PRL, 103, 148101 (2009)

[2] Rafai et al., PRL 104, 098102 (2010)

[3] Guasto et al., PRL, 105, 168102 (2010)