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Hi Vaclav,I am not sure that you can do everything with the DEM! You would like to have a quasi perfect static case by using a dynamic method... Whatever the method you use to damp particle movements I suspect the system to reach a vanishing value of kinetic energy asymptotically. Thus, if it the case, you can wait a very long time to obtain values of kinetic energy as small as you want...
But DEM is not the only method to perform discrete computations and static method based only on geometrical aspects without integrating Newton's law, allow to perform very accurate computations (for instance about the definitions of contact). See for intance the works done by Roux and Combe.
Good luck! Luc Václav Šmilauer a écrit :
Hi, I need to reach as much as possible equilibrium state, with zero motion. When using cundall's damping, I get kinetic energy dropping from 1e-3 to 1e-9, but not any lower. I suspect the cause to be the fact that cundall's damping makes force greater against the current velocity; that can lead to oscillations at the frequency of 2 iterations, if the force is such that it reverses the sense of velocity during one interation, then again etc. I suspect the same will be true for the unbalanced force measure. 1. Is someone using some sort of viscous damping to avoid this? 2. I could try to make cundall's damping to always diminish the force iff the coefficient is <0 (.e.g damping==-.3 would mean to always reduce the force to ×.7), what do you think? Regards, Vaclav _______________________________________________ Mailing list: https://launchpad.net/~yade-users Post to : yade-users@xxxxxxxxxxxxxxxxxxx Unsubscribe : https://launchpad.net/~yade-users More help : https://help.launchpad.net/ListHelp
-- Luc Sibille Université de Nantes - Laboratoire GeM UMR CNRS IUT de Saint Nazaire 58, rue Michel-Ange - BP 420 44606 Saint-Nazaire Cedex, France Tel: +33 (0)2 40 17 81 78
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