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This is a confusing take on lift. To explain lift intuitively we need two ingredients: the Laplace equation and the Kutta condition.

Most people have an intuitive understanding of the Laplace equation. For example lightning usually hits the peak of mountains. The reason is that in solutions of Laplace equations, field gradient is proportional to curvature. In fluid dynamics, this field is called the stream function. The top of airfoil is more curved than the bottom so the stream function gradient is higher on top which results in higher wind speeds over airfoil.

But the second ingredient is the Kutta condition which represents viscosity. If there were no viscosity, there would be no lift. The Kutta condition is applied to the tail (trailing edge) of airfoil. Without Kutta condition, the speed at the trailing edge would be infinity (because of Laplace equations. Speed around sharp corners is inevitably infinite). Viscosity prevents infinite velocities so we apply another condition at the trailing edge to make the air velocity smooth.

It's kind of complicated and I agree that there is no simple explanation to lift, but if you think about it for a little while, it's not that hard to grasp.




A flat plate generates lift, though, so the curvature is incidental.


That's in interesting observation. Yes, the same thing happens at the leading edge of a flat plate due to curvature resulting in flow separation and a vortex bubble on the top surface. If the flow doesn't separate, the velocity at the front (leading) edge of the plate will be infinity.

The result is a vortex bubble over the flat surface which effectively changes its geometry and aerodynamic behavior. See figure 2-12 in the following link:

http://heli-air.net/2016/02/13/inclined-flat-plate/




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