Quote:
Originally Posted by JulianEdgar
I am sorry, but that's just absurd.
Tuft behaviour doesn't match with what you describe (unless one subscribes to your logical contortions - eg attached flow shown by tufts isn't really attached flow if it's caused by a downwash) and measured pressures don't match at all with what you claim occurs.
That's the issue - in the real world, your theories about what is happening simply don't stack up.
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* ' [P]seudo-Jaray shapes, called fastbacks... with steep-sloping rear end, produces two distinct longitudinal vortices. Due to the downwash induced by these trailing vortices, the flow along the longitudinal mid-section of the car remains attached over a long path; however ,a high vortex - induced drag is produced so that the total drag is higher than for the true Jaray shapes.'
( Page-18, Hucho )
* the behavior of the tufts is an artifact of downwash.
* the downwash is a symptom of separation-induced attached, counter-rotating, longitudinal vortices.
* the air does not 'wrap' over the camber of the 911 roofline.
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This is where your logic goes off the rails!
* In 1965, the 911's Cd 0.40 'represented an improvement' over the box-shaped bodies with drag coefficients between 0.6 and 0.8' ( Hucho,page-18)
* If the air did 'wrap' over the 911 contour, the highest pressure would exist there, not the lowest. ( Hucho page-2)
* We know this from the photograph you use of the VW XL1.
* Hucho introduces Bernoulli on page 50 and 51.
* Bernoulli's concept of 'isoenergetic' streamlines is absolutely critical to your mastery of automotive aerodynamics.
* The Bernoulli Equation is on page-51.
* Your theory of 'air wrapping' completely falls apart, upon the evidence of the Bernoulli Equation.
* Your theory is a scientific impossibility.
* I didn't create the science, I'm just a messenger. Who you'd like to kill, on account of the message.
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*Every time Hucho drops a name, the automotive aerodynamicist is tasked with learning everything they can about that person's aero contribution ( Hucho, page-1, Preface )
You appear to have utter disdain for any research done before 20-30 years ago, while Hucho admonishes you to know virtually everything you can possibly get your hands on,regardless of chronology.
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You've done so well with so many aspects of your recent book. If you can only master the fluid mechanics a bit better, there's no telling, the even greater contribution you can make.
