Rolling and ordering of micro rods in shear flow induced by rod wall interactions†

Dynamics of micro particles close to interfaces is a relevant topic in Soft Matter. Translational and rotational dynamics of particles possessing different shapes govern a broad range of interfacial phenomena from biofilm formation, drug delivery and particle active rolling motion. These dynamics usually occur in the presence of external fields such as shear flows, electric fields and gravity. By experiments and theoretical models, we investigate the rolling and translational motion of rod-shaped micro particles close to a solid wall in the presence or absence of a shear flow. Hydrodynamics, long-range surface forces and Brownian motion act on the micro rods, which show non-trivial dynamics such as translational motion orthogonal to the flow direction and preferential ordering with the rod long axis perpendicular to the flow direction.