Gogo - tell your wife she thinks like a scientist
(that's a compliment in this case) That method is how Osborn Reynolds (whom the Reynolds Number which is a measure of turbulence in fluid flows is named after) did his original experiments in the latter 1800s. He used a glass pipe and inject dye into the center of the flow while varying the velocity to see the affects of velocity on turbulence. This same general method is still in use today (a staple of college labs for introduction to fluid dynamics). Higher end research now uses special dyes and lasers for investigation into turbulence affects.
Attached is a
rough drawing of what you would see when injecting ink into the center of a channel with fluid flowing with laminar and turbulent flow. Notice in the case of laminar flow, the ink will remain as a well defined stream as it progresses down the channel. In the turbulent flow, you can see how it begin breaking up into eddies and at some point down the length of the channel would be mixed into the water uniformly - just a nice reddish tinted water.
Remember this will occur even without the need any turbulence inducing surfaces. (which leads us into part two of this)