Dynamics of C-Shaped Particles Moving Through an Obstacle Field

We experimentally study the motion of C-shaped superellipse sector particles (SeSPs) as they fall through an obstacle array. SeSPs are two-dimensional particles parameterized by corner sharpness, aspect ratio, and opening angle; these parameters are sufficient to represent a large variety of shapes, including discs, rods, and concave and convex particles. Our obstacle array consists of circular pegs (cm-regime) placed with rhombic symmetry and a spacing slightly larger than the SeSP diameter. We use particle tracking to map SeSP translational and rotational motion, investigating how peg-particle interactions change the particle trajectory of a single particle moving through the array. Because of a concave particle shape, single particles can be arrested by a single peg, behavior not seen in circular or elliptical particles. From there, we move on to study collective motions of multiple particles, investigating cooperative motions that result in clogging and jamming, both locally in an isolated region of space and globally, arresting the bulk flow.