You're trying to compare the surface energy and boundary layer effects of water with air, which is not a good thing to do on something of the size we're talking about.
You don't need a special shape to make the air turn around, it wants to do that on it's own when flowing over such an abrupt change in contour. That's why I was saying that you could make the cowl-cooling concept work if you designed the hood and wiper cowl area specifically to do that.

If you're getting better cooling through raising the hood edge, it's because air is getting drawn in at that point and exiting through the bottom of the car, not exiting at the hood edge I'd imagine.
I'm just very, very skeptical that you could make a large enough pressure difference in that area to get air to exit out of there. It should work great at low speeds and at stoplights though, like I said before.