We present the equations obeyed by contacts forces in a granular system solved by the Contact Dynamics algorithm. We consider their resolution in a very simple case of cohesive interaction, i.e.for a straightforward two-body 2D normal collision. The equations predict that increasing time steps should coincide with an increase of 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. A discussion on how a seemingly purely numerical quantity may end up being a non-trivial ingredient in the physics of the simulated system ensues
