Alternative permeability values during the compaction

Asked by Soheil Safari

Hello everyone,

Hope you are doing well.

Regarding my previous question about the wrong permeability values during the compaction [1] which is not solved yet, I tried to import the packing in each step and use flowengine function to obtain the permeability.
But then I have received alternating values as well which is weird because the porosity decreases by passing the time.

I tried to follow the [2] for the modeling.
Should I change any boundary condition?

I am grateful for any hints or insights into this issue.

Here is my code:

from __future__ import print_function
from builtins import range
from yade import pack, export, ymport

compFricDegree = 3 # initial contact friction during the confining phase
finalFricDegree = 30 # contact friction during the deviatoric loading
mn,mx=Vector3(0,0,0),Vector3(1,1,2) # corners of the initial packing


spheres = ymport.text('filename.txt', shift=Vector3(0, 0, 0), scale=1.0)

O.engines = [
        FlowEngine(dead=1, label="flow"), #introduced as a dead engine for the moment, see 2nd section

#B. Activate flow engine and set boundary conditions in order to get permeability
flow.dead = 0
flow.defTolerance = 0.3
flow.meshUpdateInterval = 200
flow.useSolver = 3
flow.permeabilityFactor = 1
flow.viscosity = 10
flow.bndCondIsPressure = [0, 0, 1, 1, 0, 0]
flow.bndCondValue = [0, 0, 1, 0, 0, 0]
flow.boundaryUseMaxMin = [0, 0, 0, 0, 0, 0]
O.dt = 0.1e-3
O.dynDt = False, 1)
Qin = flow.getBoundaryFlux(5)
Qout = flow.getBoundaryFlux(4)
permeability = abs(Qin) / 1.e-4 #size is one, we compute K=V/∇H
print("Qin=", Qin, " Qout=", Qout, " permeability=", permeability)


Many thanks in advance.

Best regards,


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