They're not sharp and angular as Mitsu specified. They are soft and rounded. If they produce vortices, they will probably be weak and poorly formed. Too round and they just make turbulence, which is what the antenna base in the middle is doing. Plus the leading edge of the bar is acting like a stall strip, tripping the airflow right at the point you're trying to keep it attached. Might be a good application for VGs. Might not be a good implementation of VGs.
How do you learn more? Look at other applications.
I would be hesitant to call aircraft an alternate application. Last time I checked aircraft weren't designed to cruise down the highway at 70mph. But if I ever want to get my car to takeoff and cruise at 500mph and 35000 ft, I'll look at what airplanes are doing.
We only have one example but it's not necessarily a bad one. I wouldn't be surprised if WRC cars had them.
I would be hesitant to call aircraft an alternate application. Last time I checked aircraft weren't designed to cruise down the highway at 70mph.
Most of the aircraft in the world travel less than 200 mph and lots barely make 100 mph. Reducing drag on a car is a convenience. Reducing drag on an airplane is a necessity.
I wonder if these would help on the roof of my Dodge GrandCaravan?
I suspect not. I'm going to try and sharpen the trailing edge of the roof of my Caravan like the Honda Odessy. Sort of a little kamback. It seems to be a recurring theme on a whole host of current model cars. I've debated retrofitting the aft wing that some Caravans come with, but can't find out if it is functional or decorative.