# Permeability

Asked by Guilherme das Neves Seguro on 2020-05-09

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:

(main code: hydraulicInjection_plane.py)

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

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2020-05-09
2020-05-17
 Robert Caulk (rcaulk) said on 2020-05-17: #1

Hello,

Please refrain from asking us to follow links as you've done here [1]. Especially links that you've elected to selectively gard people from accessing. There are many reasons including the fact that this entire thread (and all work performed by the people assisting you) becomes irrelevant the moment you turn that link off, the inability for launchpad to find keywords in that link, and the spirit of open source.

If you wish to obtain open-source help on an open-source forum, please participate in our open-source mentality.

Cheers,

Robert

 Guilherme das Neves Seguro (guilhermeseguro) said on 2020-05-18: #2

Hello mr Caulk;

I'm sorry for my lack of attention on the settings for the link shared in [1], but now I've corrected my mistake. It was supposed to be an open link from the beggining.

Cheers

G. Seguro