Spheres go outside box

Hi Nait,

One solution could be to decrease time step. Your material has very low
stiffness, so the time step computed from stiffness is too high to
represent correctly the "collision" time step between spheres and box. Or
increase your stiffness (maybe this is even better).

Let us know if this was the issue :-)

Good luck
Jan
Dne 27.10.2012 12:16 "Nait" <email address hidden>
napsal(a):

> New question #212480 on Yade:
> https://answers.launchpad.net/yade/+question/212480
>
> Hi,
>
> I have encountered something strange when conducting gravity deposition:
> some particles will go outside the box.
> Can you give some suggestions for solving this problem?
>
> Thanks.
>
> Nait
>
>
> My script is as following:
>
> ####SCRIPT####
>
> from yade import pack
>
>
> rm = 0.8
> rr = 0.6
> compFricDegree = 30
> finalFricDegree = 30
>
> stabilityThreshold=0.01
>
> young=5e6
> mn,mx=Vector3(0,0,0),Vector3(20,80,200)
> mxp = Vector3(20,80,150)
> mnp = Vector3(20,80,90)
>
> thick = 0.01
> targetporosity = 0.5
>
>
> O.materials.append(FrictMat(young=young,poisson=0.5,frictionAngle=radians(compFricDegree),density=2600,label='spheres'))
>
> O.materials.append(FrictMat(young=young,poisson=0.5,frictionAngle=0,density=0,label='walls'))
>
>
> walls=utils.aabbWalls([mn,mx],thickness=thick,material='walls')
> wallIds=O.bodies.append(walls)
>
>
> sp=pack.SpherePack()
> sp.makeCloud(mn,mxp,rMean=rm,rRelFuzz=rr,porosity=targetporosity)
>
>
> O.bodies.append([utils.sphere(center,rad,material='spheres') for
> center,rad in sp])
>
>
> O.dt=.5*utils.PWaveTimeStep() # initial timestep, to not explode right away
> O.usesTimeStepper=True
>
>
> O.engines=[
> ForceResetter(),
> InsertionSortCollider([Bo1_Sphere_Aabb(),Bo1_Box_Aabb()]),
> InteractionLoop(
> # handle sphere+sphere and facet+sphere collisions
> [Ig2_Sphere_Sphere_ScGeom(),Ig2_Box_Sphere_ScGeom()],
> [Ip2_FrictMat_FrictMat_FrictPhys()],
> [Law2_ScGeom_FrictPhys_CundallStrack()]
> ),
> GravityEngine(gravity=(0,0,-9.81)),
> NewtonIntegrator(damping=0.6),
> ]
>
> O.run(2000, True)
>
> while 1:
> O.run(500, True)
> unb=unbalancedForce()
> print 'unbalanced force:',unb
> if unb<0.01:
> break
>
> yade.qt.Controller(), yade.qt.View()
>
> ####END OF SCRIPT####
>
>
>
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