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[Jason Hsin <question646457@xxxxxxxxxxxxxxxxxxxxx>]

New question #646457 on Yade:
https://answers.launchpad.net/yade/+question/646457

Hi,

I'm currently  following along the paper "Benchmark tests for verifying discrete element modelling codes at particle impact level" by Y. C. Chung · J. Y. Ooi to verify yade as asked by my supervisor. In the benchmark test 8, it seeks to simulate the impact of two differently sized spheres with a constant normal velocity and varying angular velocities. However, from the code i had, the recoil vs. incident value seems to be quite off. I'm quite new to both yade and python, any help is appreciated! 

the following is my script:

#benchmarks 8
from yade import plot
import math
import sys
import numpy as np

al_alloy=FrictMat(
	young=7.00e10,
	poisson=0.33,
	frictionAngle=np.arctan(0.40),
	density=2700,
	label='al_Mat')
O.materials.append(al_alloy)

dense_al=FrictMat(
	young=7.00e10,
	poisson=0.33,
	frictionAngle=np.arctan(0.40),
	density=2700*1000,
	label='al_dense')
O.materials.append(dense_al)

#nylon=FrictMat(
	#young=2.5e9,
	#poisson=0.40,
	#frictionAngle=np.arctan(0.4),
	#density=1000,
	#label'nylon_Mat')
#O.materials.append(nylon)

r=0.1
ang=4
vst=r*ang
incident=vst/0.2
O.bodies.append([
	sphere(center=(0,0,0),radius=r,material='al_Mat'),
	sphere(center=(0,0.65,0),radius=r*5,material='al_dense')
	])

O.bodies[0].state.vel=(0,0.2,0)
O.bodies[0].state.angVel[0]=ang

#vy=O.bodies[0].state.vel[1]
#vz=O.bodies[0].state.vel[2]
#recoil=vz/vy


O.engines=[
ForceResetter(),
InsertionSortCollider([Bo1_Sphere_Aabb()]),
InteractionLoop(
	[Ig2_Sphere_Sphere_ScGeom()],
	[Ip2_FrictMat_FrictMat_MindlinPhys(en=0.5)],
	[Law2_ScGeom_MindlinPhys_Mindlin()]
	),
NewtonIntegrator(damping=0.0,gravity=(0,0,0)),
PyRunner(command='recoilangle()',iterPeriod=1)
]

O.dt=0.1*utils.PWaveTimeStep()

def recoilangle():
	vy=O.bodies[0].state.vel[1]
	vz=O.bodies[0].state.vel[2]
	angular=O.bodies[0].state.angVel[0]
	vst=vz-0.2*angular
	recoil=vst/vy
	print 'Vcn:',O.bodies[0].state.vel[1],'Vct:',O.bodies[0].state.vel[2],'Angular:',O.bodies[0].state.angVel[0],'incident:',incident,'recoil angle:',recoil

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