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[Christian Jakob <1362090@xxxxxxxxxxxxxxxxxx>]

> You need to assign the walls as boundary conditions, just like in the oedometer example:
> flow.boundaryUseMaxMin=[0,0,0,0,0,0]

I did so, but this messages occur:

...
Starting calculation, number of steps: 50000000
6 : Vh==NULL!! id=6 Point=0.000512399 0.00124487 0.00125213 rad=3.15073e-05
7 : Vh==NULL!! id=7 Point=0.000587947 0.000954619 0.000983527 rad=0.000124813
8 : Vh==NULL!! id=8 Point=0.00146642 0.000434536 0.00102062 rad=7.286e-05
9 : Vh==NULL!! id=9 Point=0.00151061 0.0011991 0.000915917 rad=9.27561e-05
10 : Vh==NULL!! id=10 Point=0.00160129 0.00132019 0.00131859 rad=0.000116441
...
279 : Vh==NULL!! id=279 Point=-nan -nan -nan rad=5.56929e-05
280 : Vh==NULL!! id=280 Point=-nan -nan -nan rad=8.59516e-05
281 : Vh==NULL!! id=281 Point=-nan -nan -nan rad=9.2951e-05
282 : Vh==NULL!! id=282 Point=-nan -nan -nan rad=0.000119065
CHOLMOD error: invalid xtype
CHOLMOD error: argument missing
Segmentation fault

hm ...

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https://bugs.launchpad.net/bugs/1362090

Title:
  problem with pressure calculation in PFV cells

Status in Yet Another Dynamic Engine:
  New

Bug description:
  Hi,

  I want to get the pore pressure of a saturated soil sample in an
  undrained triaxial test when the sample volume is decreasing.

  ...
  TriaxialStressController(thickness=0,stressMask=7,internalCompaction=False,label='triax')
  ...

  	triax.goal1 = 35000
  	triax.goal2 = 35000
  	triax.goal3 = 70000
  	triax.wall_back_activated = False
  ...
  	flow.viscosity = 1.3e-3
  	flow.fluidBulkModulus = 2e9
  	flow.bndCondValue=[0,0,0,0,0,0]
  	flow.bndCondIsPressure=[0,0,0,0,0,0]
  ...

  For one of my simulations a decrease of ca. 1,8 % in porosity (=-dV/V)
  is obtained. When I calculate corresponding pressure increase I get

  dp = K*(-dV/V) = 2e9*0.018 = 36000000 Pa

  But the output from PFV shows maximum average pressures around of 16
  Pa (not MPa!). As long as I use SI units the output of
  flow.averagePressure() should be Pa, right?

  So is there a problem in the code or did I miss something in the
  compressibility option of PFV?

  regards,

  christian

  
  ###additional info:

  I double-checked my script and did not see anything wrong. So I think
  it is on C++ side. So I was going on testing PFV method:

  I also tested a drained situation with incompressible fluid. The porosity is decreasing due to a triggered collapse of the grain structure, but the pore pressure gets negative (see attachment).
  So I think it is a bug in pressure calculation of PFV method.

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