Quote:
Originally Posted by JulianEdgar
In an email to me last week, former head of Porsche aerodynamics, Dr Thomas Wolf, puts it this way:
"According to the Coanda-Effect the air follows the curved (upper) surface. According to Newton’s first law, there must be a force which pulls the air downwards. This force is exerted to the air by the car body and pulls the air downwards. According to Newton’s third law (action = reaction) there must be a force of the same magnitude in the opposite direction acting on the body."
There he goes again - now Dr Thomas Wolf of Porsche is wrong... but of course Aerohead is right!
On my count that's the sixth professional, highly esteemed car aerodynamicist that Aerohead has said is wrong. And people here pay attention to him? That's just amazing.
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1) Best I can ascertain, the only Coanda technology to make it into the contemporary marketplace is Dyson's Coanda Air Curler hair-care product.
Coanda effect requires an auxiliary power source to power a high static pressure air-handler for the nozzle jet.
2) I know of zero production automobiles which employ this technology. Correct me if I'm mistaken.
3) The vehicle advancing through the atmosphere is all that is required to explain forebody flow.
4) Aft-body flow is dependent on the diverging exo-duct contour not being so severe that it generates too great a pressure rise. If it does, the streamlines diverge beyond the threshold with which momentum transfer through the TBL is so weak, it comes to rest, then reverses direction, moving towards the wind shield, rolling up into separated flow, eddies, then full-blown turbulence.
5) Turbulence cannot conduct momentum or pressure from the outlying streamlines, and pressure from the separation line aft, is at the pressure of the streamline outside the separation line. The source of low pressure for lift.