TIME STEPS V.S COHESION IN NON-SMOOTH CONTACT DYNAMICS ALGORITHM

We develop the equations obeyed by contacts forces in Contact Dynamics algorithm and consider their resolution in two simple cases of cohesive grains, namely two-body and three-body cohesive collisions. We show how equations predict that increasing the time step increases the effective cohesion of the systems. Numerical simulations are performed to verify the predictions, in the case of cohesive granular piles falling in the gravity field, and in the case of a simplified Newton's cradle; predictions are confirmed. We thereby present the details of Contact Dynamics equations in a nutshell, and speculate over the definition of a dimensionless "cohesive time" that would merge considerations over the cohesive properties of the simulations and considerations over their precision.