It's interesting how little we know about some of this fluid-mixing stuff still, despite the basic principles being centuries old, and simple versions of the experiments being standard school experiments. I guess they're complex enough that there's huge ranges of stuff where we don't have good enough theoretical models, so only know what's been experimentally measured? In this case, it was surprising to me for some reason that it's unknown how dispersants will function at mile-deep water pressures; surely there's some sort of model for that? Or is it just that we're not confident in the model?
Vaguely related, I ran across recently that apparently scientists don't yet fully understand the effect that makes drinks like ouzo and absinthe get cloudy-white when you add water, due to some sort of stable oil/water emulsion being produced: http://en.wikipedia.org/wiki/Ouzo_effect