Small interactive pieces that sit behind the research on the home page: the quarter-wave rule that sets a liner cell's depth, how an aerofoil lifts, and how a slat opens a high-lift wing.
A quarter-wave cell absorbs best when its depth is a quarter of the wavelength, so the fan’s blade-passing tone sets the depth. Move the sliders to see the cell change.
Cell depth drawn to scale.
Scroll to step through the stagnation point, the suction peak and the Kutta condition at the trailing edge; hover or tap to see the flow separate at stall.
On approach the slat and flap open. Air from below runs through the slat gap and re-energises the boundary layer on the main element, so the wing can fly slower without stalling.