Swimmer-tracer scattering at low Reynolds number

Understanding the stochastic dynamics of tracer particles in active fluids is important for identifying the physical properties of flow generating objects such as colloids, bacteria or algae. Here, we study both analytically and numerically the scattering of a tracer particle in different types of t...

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Veröffentlicht in:Soft matter 2010-01, Vol.6 (17), p.4268-4276
Hauptverfasser: Dunkel, Jörn, Putz, Victor B, Zaid, Irwin M, Yeomans, Julia M
Format: Artikel
Sprache:eng
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Zusammenfassung:Understanding the stochastic dynamics of tracer particles in active fluids is important for identifying the physical properties of flow generating objects such as colloids, bacteria or algae. Here, we study both analytically and numerically the scattering of a tracer particle in different types of time-dependent, hydrodynamic flow fields. Specifically, we compare the tracer motion induced by an externally driven colloid with the one generated by various self-motile, multi-sphere swimmers. Our results suggest that force-free swimmers generically induce loop-shaped tracer trajectories. The specific topological structure of these loops is determined by the hydrodynamic properties of the microswimmer. Quantitative estimates for typical experimental conditions imply that the loops survive on average even if Brownian motion effects are taken into account. Scattering of colloids by biological or artificial microswimmers may produce characteristic, loop-shaped tracer trajectories that distinguish the underlying hydrodynamic microflows.
ISSN:1744-683X
1744-6848
DOI:10.1039/c0sm00164c