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[Jérôme Duriez <question615092@xxxxxxxxxxxxxxxxxxxxx>]

Question #615092 on Yade changed:
https://answers.launchpad.net/yade/+question/615092

    Status: Open => Answered

Jérôme Duriez proposed the following answer:
Hi,

I did not completely understand your concern, but here are few points:

In "wet simulations" you should get the equality total stress = contact stress + capillary stress, where:
- the total stress are measured from the boundaries, e.g. using triaxial engines
- the contact stress is the stress contribution from ("dry") contact forces = getStress()
- the capillary stress is the stress contribution from capillary forces = getCapillaryStress()

As an *important* note, the two get*Stress() functions require the
sample volume to be passed as an argument, with getStress having a more
user friendly default behavior (picking a correct value if the user
forgets to pass one) in this regard, though

If you do not get this equality, it means you're not using correctly the
functions, or your simulation is not quasi-static.


If your concern is that you have very low capillary stress, the answer is still the same as in previous questions: you have too big particles (for classical surface tension values). Play with small particle sizes, as unsaturated experimentalists consider fine soils and not gravel.

If you wish, you may actually also try to construct the Soil Water
Characteristic Curve of your numerical sample (in this pendular regime)
to check if you have "significant" capillary pressure * saturation
product values. If not, it means again your particle sizes are too big.

Jerome

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