Dresden 2017 – scientific programme

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BP: Fachverband Biologische Physik

BP 12: Microswimmers I (Joint Session DY/BP)

BP 12.6: Talk

Tuesday, March 21, 2017, 11:00–11:15, HÜL 186

Intermediate scattering function of an anisotropic circle swimmer — •Christina Kurzthaler and Thomas Franosch — Institut für theoretische Physik, Universität Innsbruck, Technikerstraße 21A, 6020 Innsbruck, Austria

A plethora of active agents ranging from biological microswimmers to artificially synthesized self-propelled particles exhibit peculiar dynamical behavior while moving in aqueous media at low Reynolds number. These active particles are intrinsically out of equilibrium and their transport properties are highly sensitive to their body shape, the symmetry of the propulsion mechansim, and also interactions with interfaces, which all have shown to induce a chiral swimming pattern. Here, we theoretically characterize the oscillatory dynamics of these Brownian circle swimmers in terms of the directly measurable intermediate scattering function (ISF), i.e. the characteristic function of the random displacements [1]. We identify different spatiotemporal regimes reflecting the bare translational diffusion at large wavenumbers, the persistent circular motion at intermediate wavenumbers and an enhanced effective diffusion at small wavenumbers. In particular, the circular motion of the particle manifests in characteristic oscillations of the ISF away from zero in contrast to oscillations around zero that can be traced back to the persistent swimming motion only. Furthermore, we obtain an exact expression for the non-Gaussian parameter, which displays oscillations at intermediate times mirroring the chiral swimming pattern of these active agents. [1] C. Kurzthaler, S. Leitmann, T. Franosch, Scientific Reports 6, 36702 (2016).