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DY: Fachverband Dynamik und Statistische Physik

DY 31: Particulate Matter I: From microscopic interactions to collective motion (Focus session)

DY 31.1: Hauptvortrag

Mittwoch, 22. März 2017, 09:30–10:00, ZEU 118

Magnetocapillary interactions for self-assembling dynamical systems — •Nicolas Vandewalle, Galien Grosjean, and Maxime Hubert — GRASP, Institute of Physics B5a, Sart Tilman, University of Liege, B4000 Liege, Belgium

When soft ferromagnetic particles are suspended at air-water interfaces in the presence of a vertical magnetic field, dipole-dipole repulsion competes with capillary attraction such that 2d structures are self-assembling. The complex arrangements of such floating bodies are emphasized. The equilibrium distance between particles exhibits hysteresis when the applied magnetic field is modified. Irreversible processes are evidenced. By adding a horizontal and oscillating magnetic field, periodic deformations of the assembly are induced. We show herein that collective particle motions induce locomotion at low Reynolds number. The physical mechanisms and geometrical ingredients behind this cooperative locomotion are identified. These physical mechanisms can be exploited to much smaller scales, offering the possibility to create artificial and versatile microscopic swimmers. Moreover, we show that it is possible to generate complex structures that are able to capture particles, perform cargo transport, fluid mixing, etc...