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[vadim <question171223@xxxxxxxxxxxxxxxxxxxxx>]

Question #171223 on Yade changed:
https://answers.launchpad.net/yade/+question/171223

vadim posted a new comment:
I changed the model and made a "table" from just one facet:

===================================================
def fill_box():
   """ fills the box with particles """
   def create_layer(N,r,h,offset=0):
      """ N -- number of particles in the layer
          r -- radius of particles
          h -- height of the layer
          offset -- initial offset """
      if offset==0:
         offset=2*r
      ni=nj=range(int(math.sqrt(N)))
      for i in ni:
         for j in nj:
            O.bodies.append(utils.sphere((offset+j*r*3,offset+i*r*3,h),r))

   for i in range(1):
      create_layer(16,0.008,0.01+i*0.018,offset=0.01+float(random.randint(10,20))/2500)

def shake_table():
   """ move the table according to the sine law (period T=0.5) """
   global pos_table
   h=0.02*math.sin(2*pi*O.time*2)
   pos_table[2]=h
   O.bodies[8].state.pos=pos_table

# handling engines
O.engines=[
   ForceResetter(),
   InsertionSortCollider([Bo1_Sphere_Aabb(),Bo1_Facet_Aabb()]),
   InteractionLoop(
      # handle sphere+sphere and facet+sphere collisions
      [Ig2_Sphere_Sphere_L3Geom(),Ig2_Facet_Sphere_L3Geom()],
      [Ip2_FrictMat_FrictMat_FrictPhys()],
      [Law2_L3Geom_FrictPhys_ElPerfPl()]
   ),
   GravityEngine(gravity=(0,0,-9.81)),
   NewtonIntegrator(damping=0.04),
   PyRunner(command='shake_table()',virtPeriod=O.dt),
]
# time step
O.dt=1e-08

#                        MAIN SCENARIO

# Create a box with no roof
O.bodies.append(utils.facetBox((0.05,0.05,0.06),(.05,.05,.1),wallMask=15))
O.materials[0].density=1500
# Create a table
O.bodies.append(utils.facet([(0.15,-0.1,0),(0.15,0.2,0),(-0.15,0.05,0)],color=(1,0,0)))
# copy coordinates of the table into a global variable
pos_table=O.bodies[8].state.pos
# fill the box with spheres
fill_box()

O.saveTmp()
===================================================

Let's compare new results with the previous:

1. Old, two facet table, time step dt=1e-8:

Yade [15]: O.run(2000000)
Yade [16]: O.time
       -> [16]: 0.020000000000648145
Yade [17]: O.bodies[15].state.vel
       -> [17]: Vector3(0,0,3.0783555450742548)

2. New, one facet table, time step dt=1e-8:

Yade [1]: O.run(2000000)
Yade [2]: O.time
      ->  [2]: 0.020000000000648145
Yade [3]: O.bodies[15].state.vel
      ->  [3]: Vector3(0,0,3.6318959155341539)

Conclusions. Number of facets doesn't matter. Yade doesn't work out
sphere/facet interactions properly. Maybe I can use a sphere with huge
radius instead of the facet?

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