Collision dynamics of wet solids: rebound and rotation

Knowledge about collision dynamics and energy dissipation during particle collision is fundamental for the description of particulate processes. However, such knowledge is still missing for particulate processes that involve liquids. Therefore, in this work rebound behavior of particles impacting normally or obliquely on a wet target plate is investigated experimentally via measuring the coefficient of restitution. In real processes, collisions are mostly associated with particle (initial) rotation, which makes the collision dynamics more complex than just translational energy dissipation. Thus, a focus of this work is on analysis of particle rotation and its influence on normal and tangential coefficient of restitution.The normal coefficient of restitution was found to be independent of particle initial rotation, but decreases strongly with application of a liquid layer. The tangential coefficient of restitution, on the contrary, is strongly dependent on initial rotation. Initial rotation in direction of rolling leads to an increase of translational tangential velocity, resulting from the conversion of rotational energy to kinetic energy in tangential direction. Accordingly, initial rotational velocity decreases after collision. During collisions without initial rotation, on the contrary, kinetic energy in tangential direction is converted to rotational energy due to friction.