Berlin 2018 – wissenschaftliches Programm

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BP: Fachverband Biologische Physik

BP 31: Microswimmers DY II (joint session DY/CPP/BP)

BP 31.2: Vortrag

Donnerstag, 15. März 2018, 10:15–10:30, BH-N 243

Memory-induced transition to persistent rotational motion for active colloids in viscoelastic media — •Narinder Narinder¹, Clemens Bechinger^1,2, and Juan Ruben Gomez-Solano¹ — ¹ 2.Physikalisches Institut, Universität Stuttgart, Pfaffenwaldring 57, 70569 Stuttgart, Germany — ² Max-Planck-Institute for Intelligent Systems, Heisenbergstrasse 3, 70569 Stuttgart, Germany

Life in nature is strongly conjoined with viscoelastic fluids, such as human blood and mucus. Thus, understanding the behavior of artificial microswimmers [1] in such fluids holds the potential for applications such as targeted drug delivery and cargo transport. Motivated by this, we study the dynamics of active colloids in a viscoelastic fluid. Investigating the fluid in the linear rheological response regime, with the increase in propulsion speed, a strong enhancement of the rotational diffusion of the particles is observed [2]. Further increase in the propulsion velocity of the particles leads to the emergence of a new behavior, in which particles describe well defined circular trajectories. Characterization of these orbits, reveals a non-linear dependence of the angular speed on the propulsion speed. We propose that these circular trajectories, absent in Newtonian fluids, originate from a persistent torque acting on the particles which stem from the strong coupling of particles directed motion to microstructural relaxation of the fluid.

[1] J. R. Gomez-Solano et al., Sci. Rep. 7, 14891 (2017).

[2] J. R. Gomez-Solano et al., Phys. Rev. Lett. 116, 138301 (2016).