particles fly out of boundary

Asked by Weimin Song on 2016-08-29

Dear all,

          I am packing some particles in one cylinder using randomDensePack and append one wall upwards. Why did the particles fly out of the boundary?

          BTW, warning information exists after the randomDensePack:

No suitable packing in database found, running PERIODIC compression
/home/vigoss/myYade/install/lib/x86_64-linux-gnu/yade-Unknown/py/yade/pack.py:296: FutureWarning: The default behavior will change; specify returnSpherePack=True for the new behavior, and False to get rid of this warning (your code will break in the future, however). The returned SpherePack object can be added to the simulation using SpherePack.toSimulation()
  warnings.warn('The default behavior will change; specify returnSpherePack=True for the new behavior, and False to get rid of this warning (your code will break in the future, however). The returned SpherePack object can be added to the simulation using SpherePack.toSimulation()',category=FutureWarning)

from yade import pack

O.bodies.append(wall((0,0,0.01), axis=2, sense=-1, color=(0,0,1), mask=1))

O.bodies.append(geom.facetCylinder(center=(0,0,0), radius=0.005, height=0.02, orientation=Quaternion((0, 0, 1), 0), segmentsNumber=100, wallMask=6, angleRange=None, closeGap=False, radiusTopInner=-1, radiusBottomInner=-1))
pred=pack.inCylinder(centerBottom=(0,0,-0.01),centerTop=(0,0,0.01),radius=0.005)

O.materials.append(FrictMat(young=30e9,poisson=.3,frictionAngle=.5))

spheres=pack.randomDensePack(pred,radius=0.0008,color=None,rRelFuzz=0.00005, spheresInCell=400,memoDbg=False,memoizeDb=None)

O.bodies.append(spheres)

Question information

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Status:
Solved
For:
Yade Edit question
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Solved by:
Christian Jakob
Solved:
2016-08-30
Last query:
2016-08-30
Last reply:
2016-08-30

This question was reopened

Christian Jakob (jakob-ifgt) said : #1

Hi,

Did you try to use a lower time step?

Weimin Song (wsong8) said : #2

Thanks Christian Jakob, that solved my question.

Weimin Song (wsong8) said : #3

I wonder why a lower time step could make it.

Best Christian Jakob (jakob-ifgt) said : #4

I am not familiar with randomDensePack, but as the name indicates it will generate a dense packing. So maybe particles are overlapping and high forces will act on particles. If time step is too high particles can penetrate through walls (facets).

If you want to calm your model down to adequate velocities you may also consider calm() function [1] in combination with a PyRunner[2]. An example can be found here:

https://github.com/yade/trunk/blob/master/examples/clumps/replaceByClumps-example.py#L85

Regards,

Christian

[1] https://yade-dem.org/doc/yade.utils.html?highlight=calm#yade._utils.calm
[2] https://yade-dem.org/doc/yade.wrapper.html?highlight=pyrunner#yade.wrapper.PyRunner

Weimin Song (wsong8) said : #5

Thanks Christian Jakob, that solved my question.