To cut a long story short, I used to fly gliders (sailplanes). They have very low coefficients of drag, in fact it is one of the points that most glider pilots get obsessive about
One of the 'interesting' designs on the market a few years ago was a system that eliminated the seperation bubble by tripping the laminar flow prior to the transition to turbulent flow. Nothing new there, except it used high pressure air.
The leading edge had drillings that chanelled high pressure air to the point in the upper wing surface where a series of small holes (approx 1mm) along the length of the wing let the air out just prior to the seperation point.
This had two effects. Firstly to trip the flow, and secondly to add energy to it so it reattached sooner.
This has got me thinking of an idea for hatchbacks.
Why not channel high pressure air from the front of the vehicle to the upper roof line where the air exits from a slot just below the transition point from horizontal to vertical. Also a series of holes in the roof could be used if there was seperation prior to the end of the roof line.
This would entrain the current laminar flow, or turbulent flow, add energy and possibly reduce the low pressure drag effect caused by the rear of the vehicle???
I could do a diagram if required
