Electric-field-induced ordering and pattern formation in colloidal suspensions

The long-time dynamics and pattern formation in semidilute suspensions of colloidal spheres in a viscous electrolyte under a uniform electric field are investigated using numerical simulations. The rapid chain formation that occurs in the field direction as a result of dipolar interactions is found to be followed by a slow coarsening process by which chains coalesce into hexagonal sheets and eventually rearrange to form mesoscale cellular structures, in qualitative agreement with recent experiments. The morphology and characteristic wavelength of the patterns that emerge at steady state are shown to depend on the suspension's volume fraction, electrode spacing, and field strength, suggesting additional ways of controlling effective suspension properties in practical applications.