Re: [Yade-users] [Question #275284]: bug with periodic cell of the order of the particles diameter
Question #275284 on Yade changed: https://answers.launchpad.net/yade/+question/275284 Status: Open => Expired Launchpad Janitor expired the question: This question was expired because it remained in the 'Open' state without activity for the last 15 days. -- You received this question notification because your team yade-users is an answer contact for Yade. ___ Mailing list: https://launchpad.net/~yade-users Post to : yade-users@lists.launchpad.net Unsubscribe : https://launchpad.net/~yade-users More help : https://help.launchpad.net/ListHelp
Re: [Yade-users] [Question #275284]: bug with periodic cell of the order of the particles diameter
Question #275284 on Yade changed: https://answers.launchpad.net/yade/+question/275284 Status: Needs information => Open Raphaël Maurin gave more information on the question: Hi Jerome ! Thank you for your tests ! On the picture you sent me by email, you can see very few particles at the bottom of the sample (one or two layers at most, which makes ~20 particles), but actually you introduced 120 particles ! And if you look carefully, some particles are completely overlapping... So it seems you are able to reproduce the bug. In my case, when I put the flag lateralWalls to 1 (line 11 of the script), it is completely different: you can see a deposit of about 5 layers of particles as expected, and no weird overlapping. I saw the bug you mentioned and I believe that it is linked. Do you think the new version of the insertion collider you proposed would fix the problem ? Raphael -- You received this question notification because your team yade-users is an answer contact for Yade. ___ Mailing list: https://launchpad.net/~yade-users Post to : yade-users@lists.launchpad.net Unsubscribe : https://launchpad.net/~yade-users More help : https://help.launchpad.net/ListHelp
Re: [Yade-users] [Question #275284]: bug with periodic cell of the order of the particles diameter
Question #275284 on Yade changed: https://answers.launchpad.net/yade/+question/275284 Jérôme Duriez posted a new comment: I do not know.. In my case, the major issue was at the very first step of the simulation. The insertion collider version I proposed solved at least the contact detection for this very first step. For contact detection during the simulation, the fix was probably less efficient, as I mentionned in the bug report. (different parts of the collider code apply for very first step and next steps, if I remember well) This is quite old for me now, but all my passed efforts are described on the bug report. It may be worth for you to give a try with what I proposed at that time, and it may give you some ideas to complete the fix, if necessary ? Anyway, I would be very happy if this is finally useful (hoping that the collider did not change too much in the meantime..) -- You received this question notification because your team yade-users is an answer contact for Yade. ___ Mailing list: https://launchpad.net/~yade-users Post to : yade-users@lists.launchpad.net Unsubscribe : https://launchpad.net/~yade-users More help : https://help.launchpad.net/ListHelp
Re: [Yade-users] [Question #275284]: bug with periodic cell of the order of the particles diameter
Question #275284 on Yade changed: https://answers.launchpad.net/yade/+question/275284 Status: Open => Needs information Jérôme Duriez requested more information: I gave another try with your new script (re-correcting the material definition ;-) ). With or without lateralWalls, I see: - after a first "Play" (then automatic pause), the sample stops in both cases in a state that does not really look like in equilibrium: some spheres have very few contacts with others, such that it is hard to imagine they are balanced. - after a 2d -- You received this question notification because your team yade-users is an answer contact for Yade. ___ Mailing list: https://launchpad.net/~yade-users Post to : yade-users@lists.launchpad.net Unsubscribe : https://launchpad.net/~yade-users More help : https://help.launchpad.net/ListHelp
Re: [Yade-users] [Question #275284]: bug with periodic cell of the order of the particles diameter
Question #275284 on Yade changed: https://answers.launchpad.net/yade/+question/275284 Raphaël Maurin gave more information on the question: Hi Jerome, I will try to be more explicit on the way to reproduce the bug, and try to put a script that works directly ! =) Taking the script below, which is a simple gravity deposition with bi-periodic boundary condition + a possibility to break the periodicity with lateral walls when putting the flag lateralWalls equal to 1. - You run the script exactly as it is. Open the 3D viewer. Put run. After the gravity deposition, it pauses. If you press run again, it will make a simulation increment of 0.2s. When you do it, you will see (at least I see!) that the particles takes less and less space at the bottom of the sample. They actually completely overlap each other for no reason. - You can redo exactly the same with the flag lateralWalls to 1, and you will see that the problem is gone. - You can play with the script, and vary the width or the length of the system. It happens only if the width or the length of the periodic cell is of the order of 2 or lower. I hope it is more clear ! Can you first tell me if you can reproduce the bug ? Thanks ! Raphael new script: from yade import pack, plot import math diameterPart = 6e-3 #Diameter of the particles, in meter length = 10*diameterPart#length of the stream width = 2*diameterPart #width of the stream Nlayer = 5 #nb of layers of particle, in diameter #Option to put lateral walls and break the biperiodicity lateralWalls = 0 height = 10*Nlayer*diameterPart #heigth of the periodic cell groundPosition = height/4.0 O.materials.append(ViscElMat(en=0.5, et=0., young=5e6, poisson=0.5, density=2500, frictionAngle=0.4, label='Mat')) #O.materials.append(FrictMat(young=5e6, poisson=0.5, density=2500, frictionAngle=0.4, label='Mat')) #Definition of the semi-periodic cell O.periodic = True O.cell.setBox(length,width,height) #To be compatible with lateral walls leftLimitY = 0.0 rightLimitY = width centerLimitY = width/2.0 #If lateralWalls, add the walls and increase the cell size to avoid particle touching the walls to appear on the other side if lateralWalls: #Warn the user print '\nlateralWalls option activated: mono-periodic boundary condition only !\n' #Increase the cell size O.cell.setBox(length,width+2*diameterPart,height) #Modify accordingly the position of the center of the cell and the wall right and left position leftLimitY = diameterPart rightLimitY = width+diameterPart centerLimitY = diameterPart + width/2.0 #Define the wall and add to the simulation sidePlaneL = box(center= (length/2.0,leftLimitY,height/2.0),extents=(2000,0,height*10),fixed=True,wire = True,color = (1,0,0), material = 'Mat') sidePlaneR = box(center= (length/2.0,rightLimitY,height/2.0),extents=(2000,0,height*10.0),fixed=True,wire=True, material = 'Mat',color = (0,0,1)) O.bodies.append([sidePlaneR,sidePlaneL]) # Ground reference and Wall on the side lowPlane = box(center= (length/2.0,centerLimitY,groundPosition),extents=(200,200,0),fixed=True,wire=False,color = (0.,1.,0.),material = 'Mat') #Build a plane to have a reference for the eyes O.bodies.append(lowPlane) #add to simulation #Create a loose cloud of particle inside the cell partCloud = pack.SpherePack() partVolume = pi/6.*pow(diameterPart,3.) partNumber = int(Nlayer*0.6*diameterPart*length*width/partVolume) #Volume of beads #Define the deposition height considering that the packing realised by make cloud is 0.2 depositionHeight = Nlayer*0.6/0.1*diameterPart #Consider that the packing realised by make cloud is 0.2 partCloud.makeCloud(minCorner=(0,leftLimitY,groundPosition+diameterPart+1e-4),maxCorner=(length,rightLimitY,groundPosition+depositionHeight),rRelFuzz=0., rMean=diameterPart/2.0, num = partNumber) partCloud.toSimulation(material='Mat') # SIMULATION LOOP# # O.engines = [ ForceResetter(), InsertionSortCollider([Bo1_Sphere_Aabb(), Bo1_Wall_Aabb(),Bo1_Facet_Aabb(),Bo1_Box_Aabb()],label='contactDetection',allowBiggerThanPeriod = True), InteractionLoop( [Ig2_Sphere_Sphere_ScGeom(), Ig2_Box_Sphere_ScGeom()], [Ip2_ViscElMat_ViscElMat_ViscElPhys()], [Law2_ScGeom_ViscElPhys_Basic()] # [Ig2_Sphere_Sphere_ScGeom(), Ig2_Box_Sphere_ScGeom()], #[Ip2_FrictMat_FrictMat_FrictPhys()], #[Law2_ScGeom_FrictPhys_CundallStrack()] ,label = 'interactionLoop'), PyRunner(command='gravityDeposition()',virtPeriod = 0.05,label = 'packing'), GlobalStiffnessTimeStepper(defaultDt = 1e-4, viscEl = True,timestepSafetyCoefficient = 0.7, label = 'GSTS'), NewtonIntegrator(damping=0.2, gravity= Vector3(0.,0.0,-9.81), label='newton') ] #save the initial
Re: [Yade-users] [Question #275284]: bug with periodic cell of the order of the particles diameter
Question #275284 on Yade changed: https://answers.launchpad.net/yade/+question/275284 Jérôme Duriez posted a new comment: Hi Raphael, I gave a try launching your script (after correcting the material definition ;-) ) but I still do not get exactly your issue, unfortunately. In case others are in the same case than me, would it be possible for you to isolate a simpler configuration when this issue arises ? -- You received this question notification because your team yade-users is an answer contact for Yade. ___ Mailing list: https://launchpad.net/~yade-users Post to : yade-users@lists.launchpad.net Unsubscribe : https://launchpad.net/~yade-users More help : https://help.launchpad.net/ListHelp
[Yade-users] [Question #275284]: bug with periodic cell of the order of the particles diameter
New question #275284 on Yade:
https://answers.launchpad.net/yade/+question/275284
Hi all,
There seems to be a bug in yade when simulating problems with a periodic cell
length of the order of the diameter (typically ~2d): some particles are
completely overlapping each other, and behave as a unique particle.
>From what I tested, the bug is independent from:
- the particles material properties (stiffness, viscous damping, friction
angle, density),
- the contact law (can be also pbserved with
Law2_ScGeom_FrictPhys_CundallStrack with a time step ~10^{-6})
- the time step
- the diameter of the particles
- the number of particle layers
I tested on yadedaily 1.10.0-72-d9ab58c~precise, yade from source git-3e1e44a,
on two different computer running with Ubuntu 14.04.2 LTS.
Below the message, you will find a simplified script that reproduce the
problem. It is just a gravity deposition with or without lateral walls
(lateralWalls = 1 or 0), prescribing the width and length of the periodic cell,
and the number of particle layers that you want to obtain.
The bug arises when the length or width of the periodic cell is inferior to
about 2.2d. Adding lateral walls (lateralWalls = 1 in the script) solves the
problem. For periodic cell length/width of 5d or upper, I never had any
problems.
Are you able to reproduce the bug ? If yes, do you have any idea of why that is
happening ?
Thanks in advance !
Raphael
from yade import pack, plot
import math
##
## Main parameters of the simulation
##
diameterPart = 6e-3 #Diameter of the particles, in meter
densPart = 2500 #Density of the particles, kg/m3
lengthCell = 2 #Streamwise length of the periodic cell, in diameter
widthCell = 10. #Spanwise length of the periodic cell, in diameter
Nlayer = 5 #nb of layers of particle, in diameter
#Option to put lateral walls and break the biperiodicity
lateralWalls = 0
###
## PARAMETERS DECLARATION##
###
#Geometrical configuration, define useful quantities
height = 10*Nlayer*diameterPart #heigth of the periodic cell
length = lengthCell*diameterPart#length of the stream
width = widthCell*diameterPart #width of the stream
gravityVector = Vector3(0.,0.0,-9.81)
groundPosition = height/4.0
#Particles contact law parameters
maxPressure = densPart*0.6*Nlayer*diameterPart*abs(gravityVector[2]) #Estimated
max particle pressure ("hydrostatic")
normalStiffness = maxPressure*diameterPart*1e4 #Evaluate the minimal normal
stiffness to be in the rigid particle limit (cf Roux and Combe 2002)
youngMod = normalStiffness/diameterPart #Young modulus of the particles from
the stiffness wanted.
#Material
#O.materials.append(ViscElMat(en=0.5, et=0., young=youngMod, poisson=0.5,
density=densPart, frictionAngle=0.4, label='Mat'))
O.materials.append(FrictMat(young=youngMod, poisson=0.5, density=densPart,
frictionAngle=0.4, label='Mat'))
#Definition of the semi-periodic cell
O.periodic = True
O.cell.setBox(length,width,height)
#To be compatible with lateral walls
leftLimitY = 0.0
rightLimitY = width
centerLimitY = width/2.0
#If lateralWalls, add the walls and increase the cell size to avoid particle
touching the walls to appear on the other side
if lateralWalls:
#Warn the user
print '\nlateralWalls option activated: mono-periodic boundary
condition only !\n'
#Increase the cell size
O.cell.setBox(length,width+2*diameterPart,height)
#Modify accordingly the position of the center of the cell and the wall
right and left position
leftLimitY = diameterPart
rightLimitY = width+diameterPart
centerLimitY = diameterPart + width/2.0
#Define the wall and add to the simulation
sidePlaneL = box(center=
(length/2.0,leftLimitY,height/2.0),extents=(2000,0,height*10),fixed=True,wire =
True,color = (1,0,0), material = 'Mat')
sidePlaneR = box(center=
(length/2.0,rightLimitY,height/2.0),extents=(2000,0,height*10.0),fixed=True,wire=True,
material = 'Mat',color = (0,0,1))
O.bodies.append([sidePlaneR,sidePlaneL])
# Ground reference and Wall on the side
lowPlane = box(center=
(length/2.0,centerLimitY,groundPosition),extents=(200,200,0),fixed=True,wire=False,color
= (0.,1.,0.),material = 'Mat') #Build a plane to have a reference for the eyes
O.bodies.append(lowPlane) #add to simulation
#Create a loose cloud of particle inside the cell
partCloud = pack.SpherePack()
partVolume = pi/6.*pow(diameterPart,3.)
partNumber = int(Nlayer*0.6*diameterPart*length*width/partVolume) #Volume of
beads
#Define the deposition height considering that the packing realised by make
cloud is 0.2
depositionHeight = Nlayer*0.6/0.1*diameterPart #Consider that the packing
realised by make cloud is 0.2
#Create a cloud of partNumber particles PHF change to 0.1
