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[Cloud <question680689@xxxxxxxxxxxxxxxxxxxxx>]

Question #680689 on Yade changed:
https://answers.launchpad.net/yade/+question/680689

    Status: Needs information => Open

Cloud gave more information on the question:
Hi Jan,

My bad. 
My question is that Why is it very time-consuming to converge after the box size is modified to be larger ?(mn,mx=Vector3(0,0,0),Vector3(1e-3,1e-3,1e-3) -> Vector3(0,0,0),Vector3(1e-2,1e-2,1e-2)) .

>in the second case, the situation is 1000x larger (probably having
1000x more particles). No surprise it takes longer..

Yes, I agree. My setting is
sp.makeCloud(mn,mx,-1,1.0/7.0,num_spheres=10000,False,porosity,seed=1),so
the number of particles is 10000.

>Also please be more specific what "long time" and "hard to reach"
means. More real time? virtual time? it converges slower to equilibrium?
does not converge at all? ..

I have tried the following situations:

1) use GlobalStiffnessTimeStepper first: it's easy to converge to
equilibrium when the box size is ((0,0,0),(1e-3,1e-3,1e-3)); it can not
coverge at all when ((0,0,0),(1e-2,1e-2,1e-2)).(always unbalanced force:
nan  mean stress:  nan)

2) use 0.5*utils.PWaveTimeStep(): it's also easy to converge to
equilibrium when the box size is ((0,0,0),(1e-3,1e-3,1e-3)); it can not
coverge at all when ((0,0,0),(1e-2,1e-2,1e-2)).(always unbalanced force:
nan  mean stress:  nan)

3) try to set a timestep(for example O.dt = 1e-7 or some other values, i
don't know how to set a proper value): something similar happened:
smaller size is OK, bigger one  takes a long real time to converge.

cheers,
Cloud

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