Single-particle model for a granular ratchet

A simple model for a granular ratchet corresponding to a single grain bouncing off a vertically vibrating sawtooth-like base is studied. Depending on the vibration strength, the sawtooth roughness and the restitution coefficient, horizontal transport in both the preferred and unfavoured directions is observed. A phase diagram indicating the regions in parameter space where each of the three possible regimes (no current, normal current, and current reversal) occurs is presented.