Controlled Fluidization, Mobility and Clogging in Obstacle Arrays Using Periodic Perturbations

We show that the clogging susceptibility and flow of particles moving through a random obstacle array can be controlled with a transverse or longitudinal ac drive. The flow rate can vary over several orders of magnitude, and we find both an optimal frequency and an optimal amplitude of driving that maximizes the flow. For dense arrays, at low ac frequencies a heterogeneous creeping clogged phase appears in which rearrangements between different clogged configurations occur. At intermediate frequencies a high mobility fluidized state forms, and at high frequencies the system reenters a heterogeneous frozen clogged state. These results provide a technique for optimizing flow through heterogeneous media that could also serve as the basis for a particle separation method.