Hauptseminar Soft Matter SS 2019/Microswimmers under confinement
- Microswimmers under confinement
- Philipp Stärk
- Christoph Lohrmann
When a boundary is nearby, the swimming trajectories of self-propelled active particles are greatly altered by the interactions between the swimmer and the confining surface. These interactions are not always repulsive, because the interplay of the hydrodynamic flow field generated by the swimmer and the boundary conditions imposed by the surface can yield an effective attraction. This can lead to phenomena like self-trapping and circular swimming on surfaces as well as oscillatory trajectories or a change in swimming speed.
To understand the swimmer dynamics near boundaries, first, the influence of boundaries on leading order singularities of a multipole expansion of the microswimmer-generated flow field are isolated and characterized. The results of this analytically tractable, minimalistic approach are then compared to numeric simulations of more realistic models of microswimmers.