Collision dynamics of granular particles with adhesion.

We investigate the collision of adhesive viscoelastic spheres in quasistatic approximation where the adhesive interaction is described by the Johnson, Kendall, and Roberts (JKR) theory. The collision dynamics, based on the dynamic contact force, describes both restitutive collisions quantified by the coefficient of restitution epsilon as well as aggregative collisions, characterized by the critical aggregative impact velocity gcr. Both quantities epsilon and gcr depend sensitively on the impact velocity and particle size. Our results agree well with laboratory experiments.