yade-dev team mailing list archive

[Bruno Chareyre <bruno.chareyre@xxxxxxxxxxx>]

Sometimes, StiffnessTimestepper can give irrelevant value in the first 
steps before conatcts are created (I don't know if it is the problem here).
Note you can assign GSTimeStepper::defaultDt, which will replace the 
computed value when computed > default.
In order to identify the problem, you could check what is computed in 
GSTimeStepper for each body (mass, stiffness, dt), using your prefered 
debugging method.

Bruno

boon chiaweng a écrit :
> Hi,
>
> I've enabled LOG_INFO.  The computed timestep is ridiculously large.  
> Can somebody advise me how do i progressively track down the cause?
>
> 36697 [0x7f1eecb81950] INFO yade.GlobalStiffnessTimeStepper null - 
> /home/chiab/yadeNew/Branch3/pkg/dem/Engine/GlobalEngine/GlobalStiffnessTimeStepper.cpp:170 
> computeTimeStep: computed timestep 7.56436e+153, BUT timestep is 7.59375.
>
>
> Yours,
>
> CWBoon
>
>
> ------------------------------------------------------------------------
> From: booncw@xxxxxxxxxxx
> To: yade-dev@xxxxxxxxxxxxxxxxxxx
> Date: Mon, 11 Jan 2010 19:52:20 +0800
> Subject: Re: [Yade-dev] [Bug 505523] Re: Velocity Bin
>
> Thanks Bruno. (Sorry, I forgot to clicked Reply All the first time).   
> I'm using a relatively new version right before 'bex' is changed to 
> 'fex'.  I have looped through in python:
>
> for b in O.bodies:
>     if b.shape.name == 'Sphere':
>         if b.shape['radius']<0.0001:
>              print b.shape[radius]
>
> Since nothing appears, all my radius are positive.  I've also checked 
> the smallest radii range at the start of the simulation before 
> expansion.  The radius of the smallest particles are between 0.005 and 
> 0.006.  The weird thing is that the step size at the start of the 
> simulation is as large as 200000.  I've included a screenshot
>  
>
> Yours,
>
> Boon
>
> > Date: Mon, 11 Jan 2010 11:53:04 +0100
> > From: bruno.chareyre@xxxxxxxxxxx
> > To: yade-dev@xxxxxxxxxxxxxxxxxxx
> > Subject: Re: [Yade-dev] [Bug 505523] Re: Velocity Bin
> >
> > Hi Boon,
> >
> > Are you sure your distribution is not giving negative radii or
> > something? The timestep is really (should be) the dt obtained on the
> > smallest particle. Or there is a bug in this old release.
> >
> > Bruno
> >
> > > Some particles are really small. But everytime i run a simulation, it
> > > gives me a different timestep. And sometimes it is very large, because
> > > I have very large particles in the simulation. But the calculation of
> > > the timestep should be based on the smallest particle.
> > >
> >
> >
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--
_______________
Bruno Chareyre
Associate Professor
Grenoble INP
Lab. 3SR
BP 53 - 38041, Grenoble cedex 9 - France
Tél : 33 4 56 52 86 21
Fax : 33 4 76 82 70 43
________________