This didn't quite fit in the experiments section... not really related to FE. And it's not exactly an aerodynamic modification :P But for the interested, we were given permission to fire up the water tunnel at my university last year for flow visualization. Here's some of the things we put in there.
Slight upward angle caused the flow to spiral around.
Interesting Pressure Wave Form
Now that is awesome flow attachment :P
I also have some short video clips taken by my camera... I'm waiting for Google to finish processing them. So I guess tomorrow I'll link them
Time is the best teacher. Unfortunately it kills all its students.
Actually Mattel does make a boat load of "regular" cars as diecast models. Just pu in your make and model of car in the search field of Ebay and then put diecast behind it. I'm still debating whether or not I want to shell out $15 for a diecast of my 94 hatch since it was a rare one.
Not sure but water doesn't compress as air does so you don't get a true flow model by using water. Interesting flow patterns on the under carriage flow coming out of the rear wheel wells.
You're 100% right that it won't compress - however, at low speeds (that is, sub transonic) water will act like air with respect to high pressure stagnation and high pressure "bubbles" (note apple photo).
That being said -- this tunnel moves pretty slow. Using equivalent Reynolds numbers for water--> air, the "air" flow is a tad over 3mph... Scaled for those 1/64th cars - that's less than .05mph So that tunnel really isn't a good way to find separation points on scaled object - but separation aside, you get a pretty good idea of where things are moving....