yade-users team mailing list archive

[Jan Stránský <honzik.stransky@xxxxxxxxx>]

Hi Giulia,

as usual in such cases, we have to ask you to provide us with a script
reproducing this behavior. It will show us what material you use, how you
compute time step and so on..

in my opinion, this issue is not related to collider. If you did not
mention playing with time step, I would have bet on the time step (what is
closely related to the velocity of the clinder)..

Jan


2012/9/6 Giulia Macaro <question207881@xxxxxxxxxxxxxxxxxxxxx>

> New question #207881 on Yade:
> https://answers.launchpad.net/yade/+question/207881
>
> Hi,
>
> I am running a simulation in which a constant vertical velocity is applied
> to a non-dynamic cylindrical body laying on a packing of spheres with
> periodic boundaries.
> The velocity is applied through
> TranslationEngine(velocity=-0.01,translationAxis=[0,0,1]).
> I have coded myself the cylindrical body I am working with, in a way
> similar to the chained cylinder.  It is still experimental, since I am
> still checking if it works correctly.
>
> At some point the contact force on the cylinder becomes very high, and the
> spheres in contact with it start moving extremely fast (almost as if the
> packing is exploding). See the images:
> http://www.2shared.com/photo/e7PFqYLJ/00790.html
> http://www.2shared.com/photo/wY5rowcJ/00791.html
> http://www.2shared.com/photo/0N4N71xE/00792.html
>
> 1.
> I am wondering if anybody has faced the same issue with similar
> simulations.
> I am not sure if this is a problem of the interaction sphere-cylinder, but
> it seems working fine for part of the test, and then the packing starts
> exploding.  I have tried to reduce the loading velocity and the time step,
> but it still happens.
> Could it be related to the verletDist and targetInterv, maybe because the
> particles are moving too fast and the interaction are not detected? I am
> using the default values for now.
>
> 2.
> Assuming that the problem might be the optimization with the verlet
> distance, I have few question about it.
> I see that targetInterv is =50 by default, so the distance is adjusted,
> isn't it?
> It isn't that clear the difference between the sweepLength, the verletDist
> and the sweepDist.  I understood what is the verletDist for, but then the
> other two variables seem very similar.
> And also, in which range should I vary the verletDist and targetInterv?
> Are there any references about it?
>
> Thanks for any suggestions
> Giulia
>
>
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