Permeability

Hello all;
greetings from brazil. I wrote a code that's supposed to calculate the permeability of a rock matrix using the coupled method DEM-DFN.

The rock is a cubic set fo spheres [1] and the is a plane of fracture where the fluid will flow along [2] by an imposed pressure on the bottom facet of the cube.

My goal is to measure the permeability through the rock by using the following:

O.run(1,True)
# getBoundaryFlux get the total discharge [m3/s]
Qin = flow.getBoundaryFlux(2)
Qout = flow.getBoundaryFlux(3)
# if Qout is the total discharge, we can compute k=Q*nu*Length/(Area*(Pout-Pin))
# if Qout is the flux, we can compute k=Q*nu*Length/(Pout-Pin) -> getFlux gives total discharge -> Qout (m3/s)!
permeability = abs(Qout)*flow.viscosity*Y/(X*Z) # !!! if Pout=1, Pin=0
permeability2 = flow.averageVelocity()*flow.viscosity*Y # !!! if Pout=1, Pin=0
conductivity = permeability*DENS_FLUID*9.82/flow.viscosity # K=rho*g*k/nu
print "\n\nQin=",Qin,"\nQout=",Qout,"\nOBS: ARE THEY EQUAL? IF NOT => NO FLOW!\n"
print "\n\nPermeability [m2]=",permeability,"\nHydraulic conductivity [m/s]=",conductivity, '\n\nTHE END!\n'

# # flow.saveVtk() # if you want to see the result in Paraview

But I keep getting diferent values for Qin and Qout. I've checked if the plane is placed correctly and I think it is.

- Does anyone know what could possibly be wrong with this?

A further question:
 - Should I set bndCondIsPressure as [0,0,0,0,0,0] when there is no flux? And as [0,0,1,0,0,0] when there is flux along the y axis? Or [0,0,1,1,0,0]?

All files are shared in:
https://drive.google.com/drive/folders/1G-rrLStPBemmjIBDlGO_ZVMupDyzDO5b?usp=sharing

(main code: hydraulicInjection_plane.py)

[1] 10KSpheres.spheres file
[2] Fracure_plane.png