Originally Posted by
fizz57
I am fascinated by the prevalence of the Bernoulli "explanation" and the fervour it arouses among the uninitiated, when as G&D has stated they are equivalent descriptions of the same phenomenon: one is a force approach and the other an energy approach. As anyone who has had to puzzle out the speed of a roller-coaster in school will know, the energy approach makes the calculation easier - but does "changing potential energy into kinetic energy" really provide an explanation of what is happening? Is this the source of the notion, I wonder, that aerodynamicists make their calculations in this way ("circulation") and when asked what causes the lift obviously reply "Bernoulli"? As has been pointed out above, Bernoulli has a "magical" overtone which I'm sure pilots and aerodynamicists like to have associated with their profession.
On the other hand, could there be another explanation, that the "wedge" explanation of lift does not make immediately obvious the necessity of keeping the upper-surface airflow attached, literally a matter of life and death in aviation (as well as in sailboat racing, though not so immediate). So for pilot training an explanation that emphasises this may be more useful, hand-waving and all.
The reason Bernoulli is prevalent is that its effects are directly measurable at every point on or near the aircraft. One can integrate those measurements to determine the overall forces involved. It also explains stall conditions; not so good at the turbulence. Where people fail in using it is they don't look at the entire flow-field where the air under the lift-producing wing of the typical plane is being shoved forward, decreasing the relative speed while the air above is accelerating, increasing the speed; this effect prevents the "same transit time" myth from being true. If one subtracts the airspeed distant from the aircraft it results in air moving forward under the wing, up in front, back, and then down.
Mathematically, Bernoulli is also friendly. One can set up functions where one kind of function acts as a source of fluid and another acts as a sink. Combining these can duplicate the observed flow field around aerodynamic bodies, allowing decent predictions of performance. See
https://courses.maths.ox.ac.uk/node/..._material/1967 for part of the mathematical treatment of incompressible flow.
This is the biggest advantage and avoids having to do all the Newtonian book keeping of molecular level momentum transfer in order to predict what a wing might do.