Rhythmic cluster generation in strongly driven colloidal dispersions.

We study the response of a nematic colloidal dispersion of rods to a driven probe particle which is dragged with high speed through the dispersion perpendicular to the nematic director. In front of the dragged particle, clusters of rods are generated which rhythmically grow and dissolve by rotational motion. We find evidence for a mesoscopic cluster-cluster correlation length, independent of the imposed drag speed. Our results are based on nonequilibrium Brownian dynamics computer simulations and in line with a dynamical scaling theory.