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[Gary Pekmezi <question280717@xxxxxxxxxxxxxxxxxxxxx>]

Question #280717 on Yade changed:
https://answers.launchpad.net/yade/+question/280717

    Status: Open => Answered

Gary Pekmezi proposed the following answer:
If I understand the problem correctly, below is how I would start to
approach it. Note that it is basically a trial-and-error process.

1) Start with a high angle of friction (say 45 degrees)

2) Pack a prism with 1.5x-2x the volume to abut 80% porosity . To do so
, you probably need to run it a couple of times to identify the number
of particles that will get you there.

3) Run internal compaction to a threshold confinement pressure in conjunction with scaling until the prism dimensions match the desired dimensions. If the confinement is reached prior to the required dimensions, go back to 1) and try with more spheres. Below is how I scale during internal compaction:
       initialporosity=triax.porosity                                                                                    #porosity before internal compaction
      O.run(1000, True)                                                                                                       # run some internal compaction
      packScale=(((1.0-initialporosity)/triax.porosity)**(1.0/3.0))                              # identify scaling factor from porosity change
      sp.scale(packScale)                                                                                                     # scale the packing so the psd goes back

 4) If the mean stress at this point is zero, you do not have enough
spheres. Go back to 1) and try more spheres.  Else, if the mean stress
is greater than zero proceed to the final step

5) Lower the friction angle until desired porosity is achieved

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