Dresden 2017 – wissenschaftliches Programm

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DY: Fachverband Dynamik und Statistische Physik

DY 25: Posters - Soft Particles, Microswimmers, Microfluidics

DY 25.12: Poster

Dienstag, 21. März 2017, 18:15–21:00, P3

Collective Dynamics of Squirmers in Poiseuille Flow — •Shahajhan Sorathiya and Holger Stark — Institut für Theoretische Physik, Technische Universität Berlin, Hardenbergstr. 36, 10623 Berlin,Germany.

For their immense importance and impact on human health and ecology, we aim at understanding the collective behaviour of organisms like sperms, bacteria, and algae using the squirmer model. We present numerical simulations of a large number of squirmers confined in a channel and subjected to Poiseuille flow using multi-particle collision dynamics (MPCD). Building upon our understanding how a single microswimmer behaves near the wall and in Poiseuille flow [1,2], we report on results of a parametric study varying squirmer concentration, swimming speed, and strength of background flow.

We first verified the single-squirmer motion of tumbling and swinging trajectories as derived in Ref. [1]. Increasing density we then observe different types of clustering patterns formed by pushers and pullers in Poiseuille flow. We also report on the lateral density profile, which shows a depletion in the channel center according to experiments [3]. Finally, we investigate the average squirmer orientation close to walls, which heavily depends on concentration and background flow.

[1] A. Zöttl and H. Stark, Phys. Rev. Lett 108, 218104 (2012).
K. Schaar, A. Zöttl, and H. Stark, Phys. Rev. Lett 115, 038101  (2015).
R. Rusconi, J. S. Guasto, and R. Stocker, Nature Phys. 10, 212  (2014).