New to the astronomy universe, dark flow is something to do with the velocity of galaxies. This is very ambiguous, but dark flow was only found out four years ago. Basically, the velocity is the velocity predicted by the sum in Hubble's law.
Dark Fluid is the most unclear force to scientists. Not much is known about it and I find it VERY hard to understand, probably due to my lack of knowledge in equations, but if you want to find out about dark fluid and dark flow (as this is the most ambiguous subject to me) then click this link. http://en.wikipedia.org/wiki/Dark_fluid and http://en.wikipedia.org/wiki/Dark_flow
