Multi-scale dynamics of semi-dilute and concentrated suspensions of dielectric particles in an electric field.

The multi-scale responses of the semi-dilute and concentrated suspensions of dielectric particles in an electric field are studied via a large-scale Stokesian dynamics simulation. These suspensions also share similarities with electrorheological (ER) fluids. Here, we discuss the concentration-dependent mechanisms of structural formation by probing the temporal evolution of the particle kinetics and suspension dynamics at different length scales. Below the transition concentration of 30%, we observe the well-known chain formation and subsequent slow coarsening process. Around the transition concentration, the steady-state structures show minimum anisotropy but maximum micro-and mesoscopic heterogeneity compared to other concentrations. Above that concentration, however, the suspensions directly undergo the formation of mesoscopic structures. Lastly, we investigate the effect of confinement on the suspension. It is shown that the confinement alters the structures primarily at the mesoscopic level rather than the microscale, especially at the moderately concentrated regime where the screening effect is still not dominant.