# yade-users team mailing list archive

## Re: [Question #680904]: simulation problem between sphere and polyhedra

```Question #680904 on Yade changed:

Description changed to:
hello
i was simulating the contact between sphere and polyhedra, but there is a problem:when the particle When particles come into contact with the boundary which formed by polyhedra with fixed position, it It bounces up and then fly away,moreover, the polyhedra paticle just get though the boundary, and finally only a few sphere left in the contain form by polyhedron boundary.
below is part of my code:
import random

n = FrictMat(young=1e9,poisson=.2)

O.materials.append(n)

#the boundary of particle flow
v1=((0,0,0),(0,3.2,0),(0,0,6),(0,3.2,6),(-0.1,0,0),(-0.1,3.2,0),(-0.1,0,6),(-0.1,3.2,6))
v2=((0,0,0),(0,0,6),(18,0,0),(18,0,6),(0,0.1,0),(0,0.1,6),(18,0.1,0),(18,0.1,6))
v3=((0,3.1,0),(0,3.1,6),(18,3.1,0),(18,3.1,6),(0,3.2,0),(0,3.2,6),(18,3.2,0),(18,3.2,6))
v4=((0,0,0),(0,3.2,0),(18,3.2,0),(18,0,0),(0,0,-0.1),(0,3.2,-0.1),(18,3.2,-0.1),(18,0,-0.1))
v5=((3,0.1,0),(3,3.1,0),(3,0.1,6),(3,3.1,6),(3.1,0.1,0),(3.1,3.1,0),(3.1,0.1,6),(3.1,3.1,6))
b1 = polyhedra_utils.polyhedra(material=n,v=v1,fixed=True) # you can set wire at
b2 = polyhedra_utils.polyhedra(material=n,v=v2,fixed=True)
b3 = polyhedra_utils.polyhedra(material=n,v=v3,fixed=True)
b4 = polyhedra_utils.polyhedra(material=n,v=v4,fixed=True)
wall = polyhedra_utils.polyhedra(material=n,v=v5,fixed=True)
b2.shape.wire=True

O.bodies.append((b1,b2,b3,b4,wall))

#polyhedra_utils.fillBox((0,0,0),(10,10,20),m,seed=1)

#sphere particles mixed with polyhedra
sp=pack.SpherePack()
sp.makeCloud((0,0,10),(3,3,30),psdSizes=[0.1,0.5,0.8],psdCumm=(0.5,0.8,1),seed=1)

t.state.pos = center # sets polyhedron position according to sphere position
O.bodies.append(t)
else:
O.bodies.append(t)
#simulation
O.engines = [
ForceResetter(),
InsertionSortCollider([Bo1_Polyhedra_Aabb(),Bo1_Sphere_Aabb()]),
InteractionLoop(
[Ig2_Polyhedra_Polyhedra_ScGeom(),
Ig2_Sphere_Polyhedra_ScGeom(),
Ig2_Sphere_Sphere_ScGeom()],
[Ip2_FrictMat_FrictMat_FrictPhys()],
[Law2_ScGeom_FrictPhys_CundallStrack()]  # contact law -- apply forces
),
# GravityEngine(gravity=(0,0,-9.81)),
NewtonIntegrator(damping=0.5, gravity=(0, 0, -9.81)),
PyRunner(command='checkUnbalanced()', realPeriod=3, label='checker')
]
O.dt=5e-5

i would appreciate if if you can help me

--