In MPM, I can't find where the surface tension is. The "viscous" behavior's parameters look like this:
It's a bit confusing... where is surface tension? And why is stiffness a thing for fluid? The document says stiffness is Young's Modulus, but fluid should has zero Young's Modulus, shouldn't it? Why the default value is more than 100000?
Wikipedia [en.wikipedia.org]:
a very soft material (such as a fluid) would deform without force, and would have zero Young's modulus.