While reading the
square shapes for aerodynamics thread, I noticed the Opel G90 (cD 0.22) had a weird indent on the top of its roof. At first I thought nothing of it, as it could easily just be a stylistic feature...
G90 Roof Channel
However, while looking around the internet, I came across the Daihatsu UFE (cD 0.26). I noticed it also has the same hatchback shape as the G90 and uses a similar roof channel...
UFE Roof Channel
I can only imagine the feature for three reasons: Style, Stiffness, Aerodynamics. If the first two are discounted, then I imagine they help aerodynamically by shedding vortices just as a NACA duct does.
If you excuse the poor PAINT graphic, you'll see why NACA ducts operate so efficiently. Air sheds over the sharp sides into the trough by forming vortices. I wonder if the OEM roof channels are acting as mild vortex generators?
Vortex Shedding
Maybe I'm just looking a little too deep for something that's not there. It might be something hatchback owners should look into, though. Thoughts?
- LostCause