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Old 05-21-2008, 06:53 PM
  #10  
drela
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Default RE: Bernoulli vs Newton


Here we go again...
FWIW, from a physics point of view the whole Newton vs. Bernoulli debate is rather absurd. There is no conflict between Newtons's laws and Bernoulli's law. Newton's laws explain on a microscopic level how a wing produces lift by deflecting air molecules downward causing a reaction force that we on a macroscopic level observe as lift and drag. What Bernoulli's law does is simply to keep track of the pressure and velocity changes that will occur in the vicinity of the wing as a result of the airstream being deflected.
Amen. Not only is there no conflict between Bernoulli and Newton, Bernoulli's relation IS Newton's Law integrated along a streamline. Physically they are in fact the same thing, and it takes only one straightforward calculus step to go from one to the other. For those that remember Calculus 101:

Integral [ Newton's Law ] ds -> Bernoulli
d[Bernoulli] / ds -> Newton's Law