Re: [Yade-users] [Question #685707]: Periodic flow and permeability
Question #685707 on Yade changed: https://answers.launchpad.net/yade/+question/685707 Bruno Chareyre posted a new comment: The problem is reported here: https://gitlab.com/yade- dev/trunk/issues/141 -- 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 #685707]: Periodic flow and permeability
Question #685707 on Yade changed:
https://answers.launchpad.net/yade/+question/685707
Status: Open => Answered
Bruno Chareyre proposed the following answer:
Hi,
Your script reveals that writing "flow.updateTriangulation=True" repeatedly, at
each iteration, leads to problems with periodic solver. It needs to be
investigated. Most likely some internals are not updated correctly after
assigning gradP multiple times.
In fact changing the boundary conditions repeatedly at one point in time
(i.e. in 0 iteration) is not something supposed to happen in a concrete
simulation and probably it was not anticipated.
Nevertheless, you can always use three engines instead of one, so you
are sure there is no such issue. Below is a shorter, working, version of
your script. Results with useSolver=3 (default):
average velocity=
Vector3(-4.537650575699425e-6,-4.7346547328556296e-8,-5.300733352662439e-8)
average velocity=
Vector3(-4.734654732786302e-8,-4.190262426966041e-6,5.93967279201477e-8)
average velocity=
Vector3(-5.300733352643585e-8,5.9396727919603324e-8,-4.479154269170494e-6)
Bruno
from yade import pack
O.periodic=True
O.cell.hSize=Matrix3(0.1,0,0, 0,0.1,0, 0,0,0.1)
pos_center = Vector3(0.05,0.05,0.05)
sp=pack.SpherePack()
radius=5e-3
num=sp.makeCloud((0,0,0),(.1,.1,.1),radius,.2,1000,periodic=True)
O.bodies.append([sphere(s[0],s[1]) for s in sp])
for p in [Vector3(1,0,0),Vector3(0,1,0),Vector3(0,0,1)]:
flow=PeriodicFlowEngine()
flow.imposePressure(pos_center,0)
flow.gradP=p
flow.emulateAction()
flow.saveVtk()
print("average velocity=",flow.averageVelocity())
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Re: [Yade-users] [Question #685707]: Periodic flow and permeability
Question #685707 on Yade changed:
https://answers.launchpad.net/yade/+question/685707
Status: Answered => Open
Jibril Coulibaly is still having a problem:
Hi,
Thank you very much rcaulk and bruno-chareyre for your answers. Using
flow.imposePressure() and flow.averageVelocity() provide sensible
results.
I have a couple remaining questions:
- (1) : If I try to run the script in a loop to obtain permeability in
all 3 directions, I get sensible results on the first run, then I get
zero or nan on subsequent runs. I did not get these issues when using
walls (see script below)
- (2) : Running a similar script, but reading the particles coordinates from an
external file instead, I obtain the error message: "GS did not converge in 20k
iterations (maybe because the reference pressure is zero?)".
I tried to figure it out from the code but I am not sure what this message is
warning me about.
I appreciate your help,
Jibril B. Coulibaly
###
from yade import pack,Vector3
O.periodic=True
O.cell.hSize=Matrix3(0.1,0,0, 0,0.1,0, 0,0,0.1)
pos_center = Vector3(0.05,0.05,0.05)
sp=pack.SpherePack()
radius=5e-3
num=sp.makeCloud((0,0,0),(.1,.1,.1),radius,.2,1000,periodic=True)
O.bodies.append([sphere(s[0],s[1]) for s in sp])
O.engines=[
ForceResetter(),
InsertionSortCollider([Bo1_Sphere_Aabb()],verletDist=.05*radius),
InteractionLoop(
[Ig2_Sphere_Sphere_ScGeom()],
[Ip2_FrictMat_FrictMat_FrictPhys()],
[Law2_ScGeom_FrictPhys_CundallStrack()]
),
GlobalStiffnessTimeStepper(active=1,timeStepUpdateInterval=100,timestepSafetyCoefficient=0.8),
NewtonIntegrator(damping=0.),
PeriodicFlowEngine(dead=0,label="flow")
]
O.dt=0.1e-8
O.dynDt=False
flow.defTolerance=0.3
flow.meshUpdateInterval=300
flow.useSolver=0 # Solver >0 not supported for PBC
flow.permeabilityFactor=1
flow.viscosity=1
flow.imposePressure(pos_center,1.0)
for i in [0,1,2]:
if i==0:
gradPress = Vector3(1,0,0)
elif i==1:
gradPress = Vector3(0,1,0)
elif i==2:
gradPress = Vector3(0,0,1)
flow.updateTriangulation=True
flow.gradP=gradPress
flow.updateTriangulation=True
O.run(1,1)
aveVel = flow.averageVelocity()
print("average velocity=(",aveVel[0],aveVel[1],aveVel[2],")")
###
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Re: [Yade-users] [Question #685707]: Periodic flow and permeability
Question #685707 on Yade changed: https://answers.launchpad.net/yade/+question/685707 Bruno Chareyre proposed the following answer: Hi, A periodic problem has no boundaries and therefore "flow.getBoundaryFlux(1)" is meaningless (Body #1 is not a boundary anyway). What you want is "flow.averageVelocity()". In order to impose pressure at (x,y,z) coordinates you need flow.imposePressure(). Better avoid playing with mesh elements directly since they change all the time. Cheers Bruno -- 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 #685707]: Periodic flow and permeability
Question #685707 on Yade changed: https://answers.launchpad.net/yade/+question/685707 Status: Expired => Answered Robert Caulk changed the question status: Setting to answered to avoid launchpad janitor from deleting thread. -- 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 #685707]: Periodic flow and permeability
Question #685707 on Yade changed: https://answers.launchpad.net/yade/+question/685707 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 #685707]: Periodic flow and permeability
Question #685707 on Yade changed: https://answers.launchpad.net/yade/+question/685707 Status: Answered => Open Jibril Coulibaly is still having a problem: Hello Robert, Thank you very much for your help and prompt answer. I am running Yade 2018.02b that I installed running "sudo apt-get install yade", that must be why I do not have access to "solver>0". Regarding the building of the triangulation, moving the "O.run(1,1)" before assigning pressures indeed stops the error. However, it still yields zero boundary flux, so I must be missing a piece of the setup still. I tried running a second time using "O.run(1,1)" after assigning the pressures, hoping it would run the system with the properly assigned pressures but I get a segmentation fault instead. I appreciate your guidance, Jibril B. Coulibaly -- 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 #685707]: Periodic flow and permeability
Question #685707 on Yade changed: https://answers.launchpad.net/yade/+question/685707 Status: Open => Answered Robert Caulk proposed the following answer: Hello Jibril, I'm not sure you'll find solace in my answer, but a quick review of your post lead me to these two points: 1st point: In the MWE you present, you are indexing cells before a triangulation is created. FlowEngine builds the triangulation during the first time step that it is active. So it would be necessary to make a step (O.run(1,1)) before assigning pressures. Alternatively, you could use flow.emulateAction()[1] to create the triangulation without running a mechanical timestep. 2nd point: ># Solver >0 not supported for PBC Should not be true for yadedaily versions and compiled trunk versions. Cheers, Robert [1]https://yade- dem.org/doc/yade.wrapper.html#yade.wrapper.PeriodicFlowEngine.emulateAction -- 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
