yade-users team mailing list archive

[Janek Kozicki <janek_listy@xxxxx>]

chiara modenese said:     (by the date of Mon, 5 Jul 2010 20:53:38 +0000)

> >
> > > I'm wondering if the problem is not just the time integration scheme :
> > > if a bouncing is described in 2-3 steps, the approximation of
> > > derivatives is horrible, and it might well create energy artificialy.
> > > Perhaps Cundall introduced global damping for a reason...
> >
> This is a very good point, and I have heard people here saying exactly the
> same. This is the reason why I started caring about energy conservation.
> Maybe we should modify the integration algorithm say acting on the
> velocities?
> However, if the integration scheme is affected by such approximation, then
> why with no friction energy remains constant? If it is really the
> integration scheme, I think we should have the same kind of problem also
> without friction.

Aren't integration scheme's problems mitigated by decreasing time
step several orders of magnitude? It changes the result, but doesn't
fix it. Integration problems may contribute to this
plasticDissipation bug, but I'm afraid it's not the only cause.

> PS @Bruno, I am not receiving your mails at all, I see them only in other
> people's post. Just me?

please compare with:

https://lists.launchpad.net/yade-users/threads.html

You can see that Bruno's post are in the archive. Something could be
wrong with your spam filter or such.

If you want Bruno's posts (and all posts in fact) I can send you my
whole yade-users as an mbox file, which you could import to your mail
reader.

-- 
Janek Kozicki                               http://janek.kozicki.pl/  |