The bernoulli theory of starting a long thread

On Sat, 11 Oct 2003 at 00:39:56 in message
, Jan-Olov Newborg
wrote:

You should explain that all pressure differentials only comes from
"turning the airflow", just as NASA Glenn Research shows he

That is just not true. Even in a simplistic inviscid incompressible
potential flow there are pressure differences around an aerofoil
section. They just all cancel out to a zero overall effect!

I stick to the concept that a wing section in a real flow at a lifting
angle of attack generates lift and pressures around the section. The
airflow is, of course, turned as well. Summing the pressures around the
wing will give you the lift as will finding the total deflection of the
flow (which is more difficult to measure). Mathematical relationships
between variables do not indicate cause and effect, useful as they might
be. The input variables are the angle of attack and the flow velocity.
After that it all just happens. :-)

http://www.lerc.nasa.gov/www/K-12/airplane/right2.html

Well that is a nice page, but as far as I can see the math on it is pure
Newton although it does nicely show some simple flow patterns. The
pressure results on the demo though appear to be based on Bernoulli! So
he appears to show pressure changes by Bernoulli conversion from
velocity changes!

Most of us know that the brute force solutions using powerful computers
can now give the best answers. As I understand it these calculations are
essentially step by step iterations and gradually approach closer and
closer to reality but will never be reality.

Lets get rid of "The Reversed Bernoulli use"!

What on earth is that? Since Bernoulli is an energy conserving equation
it is, by its nature, reversible.
--
Francis E-Mail reply to