Capture of particles by a flexible, granular envelope

A passive, flexible envelope can irreversibly capture comparatively small objects. As a familiar example, objects like fitted sheets and duvet covers in consumer laundry dryers often capture smaller items, like socks. The same mechanics may improve the efficiency of active processes, like the capture of prey by lunge feeding or by the extension of pseudopodia. We have developed a quasi-2D system that models this behavior: a granular chain in a dispersion of smaller, approximately circular particles. The link-scale geometry of the granular chain determines the accessible conformations, leading to a biased non-convexity. We show how the dynamics of particle capture and release depend on the chain geometry, the details of driving, and the system's boundary conditions.