Quote:
Originally Posted by aerohead
Please point out the discrepancy. I have no idea what your experience is with respect to what I've contributed, and how I can reconcile the situation.
Just a few key words could get me off dead center.
We're talking about the permalink a few spaces above, with my long explanation? # 31
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The theory moved from:
Low pressure, existing over any horizontal surface will impart lift.
Porsche's Macan would be an example. Mitsubishi's Mirage 'G' model would not.
And the separation is implicated in the Macan's Cd 0.37, vs the Mirage's Cd 0.27. Same basic roofline. One with separation, one without.
to
1) the flow separates where the truncated roof ends. You can see the streamlines continue on and the void left underneath.
2) the pressure in that void has the pressure imparted by the streamlines directly above the TBL at the point of separation.
3) since this low pressure region occurs 'over' the rear of the body below the void , it's imparting lift. Just like Taycan, Panamera, Cayman, 911,.........
4) this low pressure is also connected to the wake, lowering base pressure, increasing pressure drag, increasing overall drag.'
One theory was about separation over the roofline, the other about separation at the end of the roof. The first theory was hastily changed when the wind tunnel pic showed, of course, no such thing occurring.
Incidentally, I don't think either theory is correct.