'Straight' water filter/pump?

Question

I dont really know how to phrase this - i watched a programme on tv about how when water flows its not 'straight' but that it flows in loads of little 'lines' across each other. And there was this thing that straigtended the water out so that you could see through it. They're used in water displays apparently. Any info would be great, a name, a website. 10 points to the one with most info.

cheers

Answer 1

http://en.wikipedia.org/wiki/Streamlines...

They are called "streamlines"  See the above site and don't worry too much about the math.  The concept is simple.  It is a result of Newton's First Law of motion: a body in motion will remain in straight line motion unless acted upon by an outside force.

Consider a little cube of water, very small, it wants to move in a straight line.  All the little cubes around it want to move in a straight line.  If left alone, that is exactly what they would do.  If you dyed the little cubes so you could watch them their track would be straight lines called "streamlines."  But, put something in their way like constriction and they hit a bump or a bend so they change their direction and they get momentum in a new direction and because it is a fluid they can mix and the streamlines disappear or cross.  Left alone and given enough space (long pipe) they would straighten out again.  You can make that happen faster by putting in veins or tubes to force the streamlines back into straight lines (think of a mob of people running toward a set of doors.  As each person came out the other side of the doors, they would be running parallel to the people coming through the doors on either side of them.)