Clogging of interlocking particles in a 2D hopper

Flows of particles through constrictions occur in a broad range of situations, both in nature and in the industry. When the orifice is sufficiently small, clogging can occur, leading to an intermittent or permanent interruption of the discharge.

Over the past two decades, extensive work has been conducted to understand the physics and statistics of clog formation. Most of these studies were performed using cylindrical or spherical model particles. However, particles in practical situations often exhibit complex shapes that affect their interactions and flow behavior. In particular, shape non-convexities allow interlocking between particles, which can strongly influence the probability of clog formation.

Here, we experimentally investigate the role of particle geometry in clogging by studying the flow of a dense suspension of gear-shaped particles in a 2D microfluidic hopper. By measuring the average number of particles escaping the channel before a clog forms, we find a non-monotonic dependence of the clogging probability on a geometric shape parameter. This behavior, also reported in other systems of non-convex particles, arises from a competition between the ease of interlocking and the strength of interlocked contacts. Experimental results are compared with numerical simulations to gain further insight into the underlying arching dynamics.