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DY: Fachverband Dynamik und Statistische Physik
DY 21: Granular Matter / Contact Dynamics
DY 21.10: Talk
Wednesday, March 13, 2013, 17:30–17:45, H47
Scaling of the normal coefficient of restitution for wet impacts — •Thomas Müller1, Frank Gollwitzer1, Christof A. Krülle2, Ingo Rehberg1, and Kai Huang1 — 1Experimentalphysik V, Universität Bayreuth, 95440 Bayreuth, Germany — 2Maschinenbau und Mechatronik, Hochschule Karlsruhe - Technik und Wirtschaft, 76133 Karlsruhe, Germany
For the understanding of the dynamics of granular matter, it is important to know about the dissipation of energy due to inelastic collisions at the particle level. For dry granular matter, there are successful examples describing its dynamical behaviour based on appropriate collision models. In contrast, a continuum description for wet granulate, which considers the cohesion arising from the wetting liquid phase, is not yet established.
We investigate the coefficient of restitution (COR) by tracing a freely falling sphere that rebounds from a flat wetted surface. Our goal is to understand the energy dissipation process of a wet impact and to find a collision law which is appropriate for modelling the dynamics of granular matter. The dependence of the COR on the impact velocity as well as the properties of the particles and the liquid film is presented and discussed in terms of dimensionless numbers which characterize the interplay between inertial, viscous and surface forces. In particular, we discuss the scaling of the COR on various density and size ratios between the particle and the liquid film for liquids with different viscosities.