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[Bruno Chareyre <1362090@xxxxxxxxxxxxxxxxxx>]

> 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

It means that the geometry is weird and triangulation can't be
constructed. "nan" positions does not sound good either.
Does it happen at the first iteration after activating the fluid?
It could be the triax engine not working well when combined with fluid
flow, thus moving boundaries the wrong way. I would try to assign the
movement of the walls by myslef to see if it works correctly in that case.
Also, did you inspect the positions of particles and walls? Why are some
coordinates "nan"?
Isn't it possible to reduce the number of particles to make the script
faster. Waiting 2h to see a bug is scary.
Bruno

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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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