yade-dev team mailing list archive

[Bruno Chareyre <bruno.chareyre@xxxxxxxxxxx>]

So there is no surprise here, even if I don't understand precisely why 
this is happening.

1/ Cundall's damping (lines 76-81 - unless you saw a mistake I still 
don't see) is adapted for quasi-static simulations, where it doesn't 
affect the results when used reasonably.
2/ It is also used to speed up convergence to static equilibrium.
This damping is affecting the dynamics of systems however (if it was not 
affecting anything, it wouldn't damp...).

Now if you consider your system :
1/ it is a granular flow, not a quasi-static evolution
2/ it is permanently out of equilibrium

So, even if the impact of the damping is impressive, in your results, it 
is not the first time I see such strange behaviour in dynamic systems 
with Cundall's damping.
This type of simulation should use no damping at all. You don't need it.


Bruno





sega a e'crit :
> Hello.
> Just run ring.py which I sent previously, and you will see wrong spheres movement.
> But if you will do in python console:
>
> o=Omega()
> o.engines[7]['damped']=0
>
> you will see how it sould be...
>
> What a strange formulas on lines 76 and 81 in NewtonsDampedLaw.cpp???
>
>   


--

_______________
Chareyre Bruno
Maitre de conference

Grenoble INP
Laboratoire 3SR - bureau E145
BP 53 - 38041, Grenoble cedex 9 - France
Te'l : 33 4 56 52 86 21
Fax : 33 4 76 82 70 43
________________