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Re: Strange behavior of periodic cell


Really strange indeed, and I don't know where to start.
It seems ghost spheres are missing on one side of the cell, aren't they?
Out of curiosity, I checked what happens using velGrad/homothetic. I was really surprised because it looked like it solved the problem, but it's in fact just delaying it (see attached script). After first iteration, there are ghost spheres all around the cube, unlike in previous case.

More generaly, is it expected that users will change cell.trsf? I have the feeling that it will not be reflected properly in each place (e.g. homotheticRescale is disabled since it is based on velGrad).


Václav Šmilauer a écrit :
I'm trying to do some simulations using periodic cell. In one case, I prescribed some extension of the periodic cell, but the particles in the simulation behave really strange - the dispacement of particles si continuously increasing.

I had a look again. It looks as if kinetic energy is increasing, even
with damping=0.9.

I tried with Law2_Dem3DofGeom_FrictPhys_Basic and also
Law2_ScGeom_FrictPhys_Basic (instead of the Cpm law) and the result is
always the same: spheres bumping into each other going crazy after a
short while. What is happening??

Can someone have a look as well? Especially tracking stored elastic and
kinetic energy could be useful. (there is no plasticity involved) The
script is attached (run with -j1, it might be faster).

Weird thing.



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Bruno Chareyre
Associate Professor
ENSE3 - 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

# -*- coding: utf-8 -*-
from yade import pack, log, qt
import itertools

# create material

# create 3x3x3 particles
a=1.; r=a/6.
for i,j,k in itertools.product(range(3),repeat=3):

		## the same with other consitutive laws:
		# [Ig2_Sphere_Sphere_Dem3DofGeom(distFactor=-1)],[Ip2_CpmMat_CpmMat_CpmPhys(cohesiveThresholdIter=-1)],[Law2_Dem3DofGeom_CpmPhys_Cpm()]),
		# [Ig2_Sphere_Sphere_Dem3DofGeom()],[Ip2_FrictMat_FrictMat_FrictPhys()],[Law2_Dem3DofGeom_FrictPhys_Basic()]),

# forced compression of periodic cell along x

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