Regensburg 2007 – wissenschaftliches Programm

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DY: Fachverband Dynamik und Statistische Physik

DY 30: Poster II

DY 30.52: Poster

Donnerstag, 29. März 2007, 16:00–18:00, Poster D

Coefficient of restitution: The effect of finite duration of collisions — Thomas Schwager and •Thorsten Poeschel — Charité, Augustenburger Platz 1, 13353 Berlin

The dynamics of a granular systems may be computed by Molecular Dynamics based on the interaction forces or by event-driven Molecular Dynamics using the coefficient of restitution. Knowing the forces the coefficient of restitution can be derived by integrating Newton’s equation of motion. The end of a particle collision should be characterized by the time when the repulsive force between the particles conceals. So far, however, for simplicity it was assumed that the collision ends when the distance of the particle exceeds the sum of the radii. We show that the latter assumption leads erroneously to effective attractive forces and, thus, to an overestimation of the coefficient of restitution. Applying the improved condition for the duration of collisions, we derive the coefficient of restitution for the most frequently used particle interaction models. For the case of viscoelastic particles we find a novel dependence of the coefficient of restitution on the impact rate.