Re: [Phys-l] Bernoulli Effect

[Brian Whatcott <betwys1@sbcglobal.net>]

At 12:59 PM 12/15/2007, you wrote:

> In describing the Bernoulli effect to high school students I invariably
> get stuck on one particular question and I wonder if someone can help
> give me the "high school" words necessary to answer this question.
>
> When looking at the cross section of a wing, I have always said that the
> air flow under the wing (which is a relatively flat surface) is slower
> than the air flow over the top of the wing which is curved.  The
> question from them is "why isn't it just as likely that he air over the
> top of the wing does not speed up and simply takes a longer time to
> travel the longer distance over the curved section of the wing?".
>
> Any assistance would be welcome.  Thanks,    David Abineri

When airflow past a lifting wing section is visualized with smoke
pulses forming vertical bars, it is quite obvious that a vertical
 bar marked in the air divides and moves faster over the upper
 surface.
The bar does NOT reconnect at the trailing edge. This is not a
question of unsupported theory, but observed fact.

(Much the same effect is seen when the airfoil is tested upside
 down, but arranged to lift, by the way.)



Brian Whatcott    Altus OK    Eureka!