Berlin 2018 – scientific programme

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DY: Fachverband Dynamik und Statistische Physik

DY 8: Active Matter I (joint session DY/CPP/BP)

DY 8.10: Talk

Monday, March 12, 2018, 12:30–12:45, BH-N 243

Pattern Formation and Synchronization of Disk-Shaped Circle Swimmers — •Guo-Jun Liao and Sabine H. L. Klapp — Institut für Theoretische Physik, Technische Universität Berlin, Hardenbergstraße 36, 10623 Berlin

We computationally study a generic model of disk-shaped active Brownian particles using Brownian dynamics simulation. Each particle is driven both by constant propulsion force and torque. We investigate how these two distinct propulsions combine to influence the macroscopic structure of a colloidal system. In the regime of small propulsion torque, the active colloids exhibit motility-induced clustering [1]. As the propulsion torque becomes comparable to thermal energy, the clustering phenomenon is drastically suppressed. Moreover, although all particles are intrinsically assigned to rotate counterclockwise, a novel state of clockwise vortices emerges at an optimal value of propulsion torque. We introduce a gear argument to capture the underlying mechanism of such vortices. To obtain deeper insight into the interplay between active motion and particle alignment, an additional polar interaction is then incorporated into our model. With increasing strength and range of the polar interaction, synchronization behavior is observed. Our model bears some similarity with the Kuramoto model [2], in which oscillators are actively moving over time.
[1] I. Buttinoni et al., Phys. Rev. Lett. 110, 238301 (2013)

[2] Y. Kuramoto, Chemical Oscillations, Waves, and Turbulence, (Springer, Berlin, 1984).