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BP: Fachverband Biologische Physik

BP 24: Poster B: Active Biological Matter, Cell Mechanics, Systems Biology, Computational Biophysics, etc.

BP 24.5: Poster

Dienstag, 23. März 2021, 16:00–18:30, BPp

Hydrodynamic interactions between microswimmers and particles in viscosity gradients — •Sebastian Ziegler¹, Maxime Hubert¹, Thomas Scheel², Jens Harting², and Ana-Sunčana Smith^1,3 — ¹PULS Group, Friedrich-Alexander-University Erlangen-Nürnberg, Germany — ²Helmholtz Institute Erlangen-Nürnberg for Renewable Energy, Forschungszentrum Jülich, Germany — ³Division of Physical Chemistry, Ruder Bošković Institute Zagreb, Croatia

A common theoretical approach to model systems of microswimmers is to prescribe the swimming stroke of each individual. If the system consists of more than one device, the problem of hydrodynamic interactions becomes a purely geometric one. This limitation is overcome by prescribing the forcing instead of the stroke, as shown by our novel perturbative approach, applicable to arbitrary geometries. We elaborate the effects of nearby swimmers on the stroke, swimming speed and direction. We find that for two swimmers, a significant fraction of the parameter space results in both swimmers experiencing a boost from one another.

We furthermore study the interaction of spherical particles in fluids with viscosity gradients. Using an analytical approach we show that a particle in a linear viscosity gradient induces a locally distance-independent flow field. Moreover, we characterize the effect of asymmetric particle placement in the finite-size gradient. Finally, we study the interactions between two particles that are at different temperatures than the surrounding fluid, and calculate the first order correction to the mobility matrix in the regime of low Peclet numbers.