Abstract
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.
Highlights
Granular systems are abundant in nature and examples range from sands and powders on Earth1,2͔ to more dilute systems, termed as granular gases3–5͔, in space; planetary rings and other astrophysical objects may be mentioned in this respectsee, e.g., ͓3,6͔͒
We investigate the collision of adhesive viscoelastic spheres in quasistatic approximation where the adhesive interaction is described by the Johnson, Kendall, and RobertsJKRtheory
The collision dynamics, based on the dynamic contact force, describes both restitutive collisions quantified by the coefficient of restitution as well as aggregative collisions, characterized by the critical aggregative impact velocity gcr
Summary
Granular systems are abundant in nature and examples range from sands and powders on Earth1,2͔ to more dilute systems, termed as granular gases3–5͔, in space; planetary rings and other astrophysical objects may be mentioned in this respectsee, e.g., ͓3,6͔͒. The interaction force is a combination of elastic rebound, dissipation due to viscous deformations, and adhesion caused by the molecular van der Waals forces. The interplay between these three basic contributions leads to a rich collision behavior of adhesive, dissipative particles, which in turn determines the unusual macroscopic properties of granular systems. We assume that the characteristic times of the collision process is much larger than the dissipative relaxation time of the particles’ material This assumption allows one to express the dissipative part of the stress through the elastic stress and to develop an analytical theory. We compute the maximal impact speed at which aggregation may occur, separating the domain of restitutive collisions where particles rebound, from the domain of aggregative collisions where particles constitute a joint aggregate
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