Comment 5 for bug 1308074

The problem is getStress is trying to static_cast MindlinCapillaryPhys as a CapillaryPhys while they are independant classes.
I don't think it ever worked before. I'm surprised that it doesn't simply crash. Maybe last year you were not using Mindlin law.
Or, you were very lucky and somehow the wrong cast was giving the right value since both classes have the member fCap.

Anyway, it is fixed now [1].
You can use getCapillaryStress(mindlin=True)
Note that you should give the volume argument to.

[1] https://github.com/yade/trunk/commit/84a28bebea5a8c2a772a11ccd88934e9e6ae88fe