Granular flow enhancement in a model silo by using a pedant mobile obstacle

Abstract

It is well established that placing an obstacle near a silo outlet reduces the clogging probability in systems approaching the jamming zone, even enhancing the flow rate when the obstacle is optimally positioned. Typically, studies have focused on fixed obstacles in 2D-silo models, using spherical particles, and the underlying mechanisms driving flow rate improvements remain a topic of ongoing research. We investigate experimentally the impact of a pendant mobile obstacle on the discharge flow of lentils using a rectangular flat-bottomed silo with a thickness of several particles. Even when the silo is inside the continuous flow regime, we still observe flow maximization for an optimal obstacle height. By selecting appropriate scaling lengths, we achieve a collapse of the flow rate curves for all aperture sizes studied. Our results indicate that different silo configurations exhibit distinct flow correlations, whose type and extent are crucial for flow rate maximization. Velocity profiles indicate that the obstacle increases particle velocity in the lateral channels surrounding the obstacle. Beyond the optimal height, this effect diminishes, and a sharp drop in velocity is found. This is the first experimental confirmation of previous numerical studies. An analytical model using free-fall particle behavior to describe the flow in the lateral channels provides a good representation of the discharge rate.