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Coefficient of tangential restitution for the linear dashpot model
Volker Becker1, Thomas Schwager, Thorsten Pöschel
1Charité, Augustenburger Platz 1, D-13353 Berlin, Germany.
Summary
The linear dashpot model, popular for granular systems, assumes constant normal restitution. However, this study reveals the tangential restitution coefficient varies with impact velocity for frictional particles.
Area of Science:
- Physics
- Mechanical Engineering
- Materials Science
Background:
- The linear dashpot model is widely used for simulating granular systems due to its constant normal restitution coefficient (epsilonn).
- Investigating tangential forces is crucial for understanding granular dynamics, especially for frictional particles.
Purpose of the Study:
- To determine the tangential coefficient of restitution (epsilont) for two common tangential force models.
- To analyze the relationship between epsilont and impact velocity (g) within the context of the linear dashpot model.
Main Methods:
- Analytical derivation of epsilont.
- Numerical integration of Newton's equations of motion.
- Simulation of colliding frictional spheres.
Main Results:
- The tangential coefficient of restitution (epsilont) exhibits a pronounced dependence on impact velocity (epsilont = epsilont(g)).
- This velocity dependence is observed despite the assumption of a constant normal restitution coefficient (epsilonn = const).
Conclusions:
- The linear dashpot model, while simple for normal forces, requires careful consideration of tangential forces for accurate granular simulations.
- The derived velocity-dependent epsilont is essential for event-driven simulations involving frictional granular systems.
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