yade-users team mailing list archive

[Bruno Chareyre <bruno.chareyre@xxxxxxxxxxx>]

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.

Bruno







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