You're floating down a narrow river or stream (or lazy river for that matter)on inner tubes with your friends on a holiday weekend. Those of you old enough to are enjoying some adult beverages. Naturally, drinking said beverages leads to frequent passing of fluids into the stream. The question is this: Where in the group would you find the lowest concentration of wee? The front, back, or sides?
The front: Assuming the wee isn't flowing along with the group.
The middle: Conventional wisdom says no way.
The back: Assuming the dissolved solids in the wee are traveling at the same speed as the water or are heavy enough to sink despite the current.
I suspect the back, and here's why. I'm going to assume the wee is going to flow along with the water at the same speed as the current (as it's water soluble). I'm going to further assume that the people floating are traveling at ANY speed slower than the current (so long as they're not paddling). Because it's impossible to exceed the speed of the current without propulsion of some sort, and the presence of surface tension and drag (however minute) any given floating object should e traveling at a slightly slower speed than the water itself. Therefore, the back of the group should have a lower concentration of dissolved wee than the front or middle.
This of course assuming "laboratory" conditions concerning floor topography, debris, speed, wind, etc.
What do you think?