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Re: [Yade-dev] dissipating all energy in a packing


Václav Šmilauer a écrit :
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...
Sorry to be unclear: the kinetic energy doesn't decrease from the point
where it hits some bottom line (around 1e-9 in this case), and
oscillates around this value. I suspect the way Cundall damps motion to
be blamed. Well, I will try and see. Best, Vaclav
The critical question : is 1e-9 more than what you would get from rounding errors?
Come on, you need to compare this 1e-9 with another value!

Another possible normalisation, provided you have a speed defined somewhere (like triaxial test at constant strain) : divide by the kinetic energy of the homogeneous-continuum-like velocity field. If your configuration is purely static, I have no other idea than elastic energy.

And about Cundall's damping being "the best" (in my previous message), note that it only applies to confined packings in quasi-static conditions. As suggested by Feng, non-viscous damping gives unrealistic motions in some dynamic problems.


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