Hi, everybody, I am doing a thesis related to fluids and I have thought about smart fluids (magnetorheological and electrorheological fluids) and ferrofluids. I've read a lot about and I know well their special characteristics. However there's something I can find nowhere: do they produce force by moving? I mean. I know nowadays dampers formed with magnetorheological fluids are being strongly developed, and of course they produce an important damping force by altering their viscosity. And I have also read, in case of ferrofluids, that the flow of a ferrofluid can be achieved at a certain velocities just by changing the field applied. But, do this movement produce force? In the case that a fluid accelerated by changing fields in an specific ferrofluid devise would be guided in to a conduct with a piston, would this piston be displaced? This information is something I don't get to find and it's really relevant to my thesis. Thank you everybody for your help.